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Page 1: UM_QM2-IB_Ordner

UNISEMINAR

Page 2: UM_QM2-IB_Ordner
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Theory

Practice

Exams

Extras

Sem

inar

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 Introduction  

   

Quantitative  Methods  II  (IB)  Academic  Year  2011/2012,  Block  3  

       

   

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Uniseminar  –  Quantitative  Methods  II                                    Introduction  

Welcome  to  Uniseminar!    

IInnttrroodduuccttiioonn  

Uniseminar   offers   EExxaamm     PPrreeppaarraattiioonn     SSeemmiinnaarrss,,     SSuummmmaarryy     SSccrriippttss     aanndd    

LLeeaarrnniinngg     CCaarrddss     for  students  of  the  Maastricht  University.  It  is  our  goal  to  op-­‐

timally  prepare  you  for  your  exams  and  to  make  your  own  exam  preparation  as  

efficient  as  possible.  In  order  to  achieve  this  goal,  we  have  developed  a  system  of  

seminars  in  combination  with  an  extensive  summary  script,  which  is  proven  for  

several  years  by  now.  

In   university   it   is   often   the   case   that   there   is   a   lot   of   material   available   for   a  

course  and  that  the  importance  of  this  material  is  hard  to  evaluate.  Since  we,  as  

students,  have  made  this  experience  as  well,  you  are  provided  with  a  Uniseminar  

Summary   Script   of   the   corresponding   course.   This   folder   contains   all   exam-­‐

relevant  material  and  it  gives  you  a  good  summary  of  all  course  topics.  The  con-­‐

tent   of   the   folder   is   created  by   experienced  Master   or  PhD   students,  who  have  

taught  this  course  already  several  times.  As  a  consequence,  it  is  possible  for  you  

to   concentrate   on   the   actual   exam   preparation,   rather   than   spending   hours  

searching  and  printing  the  right  material.  

At   the   end   of   week   6   of   your   block,   normally   during   the   weekend,   our   EExxaamm    

PPrreeppaarraattiioonn     SSeemmiinnaarrss   take   place.   These   seminars   are   taught   by   above-­‐

average   students,   who   have   already   mastered   their   studies   at   the   Maastricht  

University  and  have  a  great  deal  of  experience  in  tutoring.  Since  they  have  stud-­‐

ied   and   taught   at   the   Maastricht   University   they   know   exactly   where   potential  

problems  may  lie  and  are  therefore  able  to  optimally  teach  you  the  whole  theory  

of  the  course  and  practice  perfectly  tailored  examples  with  you.  Furthermore  you  

can  bring  in  your  own  questions  during  the  seminar  and  discuss  individual  prob-­‐

lems  during  the  breaks.  

You   are   able   to   pick   up   your   SSuummmmaarryy     SSccrriipptt     aanndd     LLeeaarrnniinngg     CCaarrddss   in   ad-­‐

vance  of  the  Seminar  in  order  to  already  start  preparing  so  that  you  can  discover  

your  own  difficulties  early  enough.  Later  in  the  Seminar  you  will  then  know  what  

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Introduction                          Uniseminar  –  Quantitative  Methods  II  

your  weaknesses  are  and  be  able  to  pay  special  attention  to  these  sections  or  ask  

questions   about   it.  Our   Summary   Script   and  Learning  Cards   are  updated   every  

year  according  to  the  current  course’s  content  and  we  are  always  trying  to  opti-­‐

mize  the  folder  as  much  as  possible.  

     

AAbboouutt    UUss    

Uniseminar   was   founded   5   years   ago   by   two   students   at   the   University   of   St.  

Gallen   in   order   to   make   Exam   Preparation   more   efficient   and   coherent.   Since  

2005  we  have  expanded  our  vision  and  are  now  offering  seminars  and  material  

for  an  efficient  exam  preparation  in  Switzerland,  the  Netherlands,  Italy  and  Ger-­‐

many.  

Thanks  to  this  longstanding  experience,  we  were  able  to  build  up  a  team  of  highly  

qualified   tutors  and  editors  and  are   therefore  able   to  guarantee  high  quality  of  

exam  preparation.  

The  team  of  Uniseminar  is  grown  strongly  over  the  years  and  comprehends  sev-­‐

eral  mathematicians,  statisticians  and  economists,  who  all  bring  a  great  didactical  

experience.  All  tutors  of  Uniseminar  have  been  teaching  their  field  for  years  and  

know  exactly  what  is  important  in  order  to  optimally  prepare  and  pass  the  exam.  

 

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Uniseminar  –  Quantitative  Methods  II                                    Introduction  

SSuummmmaarryy    SSccrriipptt    This  aim  of  this  folder  is  to  support  you  with  your  exam  preparation  for  ‘Quanti-­‐

tative   Methods   II’   as   much   as   possible.   Usually   it   consists   of   five   different   sec-­‐

tions.  As  follows,  a  short  overview  of  the  content  of  this  folder:  

 

11.. TThheeoorryy::    The  Theory  Script  summarizes  the  whole  theory  of  the  course  in  

a  simple  and  understandable  way.  Concepts  are  explained  with  the  help  of  

demonstrative  examples.   It   is  structured  according  to  the  seven  weeks  of  

the  course  and  is  one  of  the  most   important  parts  of  your  exam  prepara-­‐

tion.      

2. PPrraaccttiiccee::  The  Practice  part  contains  practice  exercises  to  each  week  and  

therefore  to  each  chapter  of  the  theory  script.  By  this,  you  can  deepen  your  

theoretical  knowledge  with  practical  exercises  and  you  can  go  through  the  

exercises  of  these  topics  again,  which  you  have  not  understood  so  well  un-­‐

til  now.    

3. EExxaammss::   In  this  part  you  will   find  old  exams  of  the  Maastricht  University,  

as  well  as  one  practice  exams  constructed  by  Uniseminar.  During  the  sem-­‐

inar  you  will  then  receive  a  further  practice  exam.  

4. EExxttrraass::     In  the  Extras  part,  you  will  find  a  formula  sheet  as  well  as  an  ex-­‐

planation  of  how  to  read  off  the  statistics  tables.  

5. SSeemmiinnaarr::     In  this  part,  we  have  provided  you  with  some  notepaper  so  that  

you   can   take   notes   during   the   seminar.   Furthermore   you   will   receive   a  

fourth  practice  exam  during  the  seminar,  which  you  can  file  in  here.  In  case  

you  have  not  subscribed  for  the  Quantitative  Methods  II  seminar  yet,  you  

can  do  so  on  our  website  -­‐  www.uniseminar.nl  -­‐  at  any  time.  

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Introduction                          Uniseminar  –  Quantitative  Methods  II  

QQuuaannttiittaattiivvee    MMeetthhooddss    IIII  

The  ‘QM2’  course  treats  two  different  main  fields:  Mathematics  and  Statistics.  It  

is  the  continuation  of  QM1,  you  have  attended  and  hopefully  passed  in  your  first  

block  of  this  academic  year.  The  topics  of  the  course  build  on  QM1.  Although  we  

integrated  some  minor  parts  of  the  QM1  course,  it  is  essential  that  you  have  un-­‐

derstood   the  major   theories  and  practices  of  QM1   in  order   to  master  QM2.  De-­‐

pending  on  your  difficulties,  you  should  put  your  focus  on  certain  fields  or  topics,  

however,  do  not  forget  that  the  exam  is  equally  distributed  in  terms  of  questions  

per  topics.   It  does  not  make  any  sense  to  concentrate  on  Mathematics  only,  be-­‐

cause  this  knowledge  alone  will  not  be  sufficient  to  pass  the  exam.  

The  exam  consists  of  40  multiple  choice  questions  and  you  will  have  3  hours  time  

to  calculate   it.  As  mentioned,   the  questions  are  equally  distributed,   i.e.  you  will  

have  20  math  questions  and  20  statistics  questions.  

   

HHiinnttss    aanndd    TTrriicckkss    

Here  are  some  tips  that  may  be  helpful  for  your  exam  preparation.  Many  students  

make  typical  errors  when  preparing  for  their  first  exams  at  university.  We  there-­‐

fore  want  to  help  you  to  avoid  these  mistakes,  so  that  you  can  focus  on  the  essen-­‐

tial  stuff,  rather  than  wasting  your  time  with  a  preparation  into  the  wrong  direc-­‐

tion!  

   

HHooww    ddoo    II    ooppttiimmaallllyy    pprreeppaarree    ffoorr    aann    eexxaamm??    

The  exams  of  the  university  are  created  in  such  a  way  that  every  student  can  pass  

them  with  an  average  preparation  time.  Since  there  is  a  lot  of  content  and  time  is  

limited,   planning   is   the  basis   of   your   success.   You  don’t   need   to  be   a   genius   to  

pass  the  exam,  but  you  should  still  take  care  of  a  few  things  and  try  to  develop  a  

certain  discipline   in   the   following  weeks.   The   subsequent   hints  may  be  helpful  

for  you:  

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Uniseminar  –  Quantitative  Methods  II                                    Introduction  

TTaakkee    yyoouurr    ttiimmee!!    

It   is   totally  normal   that  you  will  be  slower   in  solving  exercises   in   the  be-­‐

ginning.  You  can  be  sure  that  you  will  improve  your  efficiency  and  velocity  

after  some  practice,  however  you  should  start  preparing  for  the  exam  early  

enough.  By  this  you  can  avoid  that  you  get  time  pressure   in  the   last  days  

before  the  exam.  

 

CCoonncceennttrraattee    oonn    pprraaccttiiccee!!    

Although   you   should   make   sure   that   you   have   understood   all   basic   con-­‐

cepts  of  the  theory,  try  to  do  as  many  exercises  and  old  exams  as  possible.  

You  will  notice  that  exam  questions  repeat  a  lot  and  that  calculations  will  

become  a  lot  easier,  if  you  do  them  the  second  time.  

 

SSttuuddyy    aalloonnee    aanndd    iinn    ggrroouuppss!!    

In  the  beginning  you  should  start  studying  and  practicing  alone  so  that  you  

know  for  sure  that  you  have  understood  most  of  the  content.  If  you  experi-­‐

ence   problems   you   should   ask   a   friend   and   you   should   try   to   solve   the  

problem  together.  Group  work  can  be  very  helpful,  especially  for  students  

with   different   capabilities.   Nevertheless,   often   it   can   also   be   very   ineffi-­‐

cient  and  you  would  do  much  better  if  you  learned  alone.  

 

DDoonn’’tt    cchheecckk    tthhee    ssoolluuttiioonnss     iimmmmeeddiiaatteellyy!!    

Take  your  time  when  doing  an  exercise  or  a  practice  exam  and  try  first  to  

solve  it  on  your  own.  It  is  important  for  your  learning  process  that  you  also  

make  mistakes,  because   it   shows  you  where  you  still  have  problems  and  

on  which  topics  you  should  concentrate.  It  is  better  to  do  the  mistakes  dur-­‐

ing  your  preparation  than  in  the  exam.  

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Introduction                          Uniseminar  –  Quantitative  Methods  II  

QQuueessttiioonnss    &&    MMiissttaakkeess    

As  soon  as  you  discover  a  mistake  or  misunderstanding  in  the  text  you  can  sub-­‐

mit   a   question   on   our   webpage   www.uniseminar.nl.   Just   log   in   under   ‘My   Ac-­‐

count’  with  your  email-­‐address  and  your  password  and  go  to  the  section  ‘Ques-­‐

tions  &  Feedback’.  Your  questions  will  be   forwarded  to  the  tutor  so  that  he  can  

optimally   tailor   the   seminar   to   your   needs.   If   it   is   an   urgent   question,   we   will  

send  you  an  answer  before  the  seminar  as  soon  as  possible.  

 

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Theory

Practice

Exams

Extras

Sem

inar

T

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 Theory  

   

Quantitative  Methods  II  (IB)  Academic  Year  2011/2012,  Block  3  

       

   

   

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Theory                                Uniseminar  –  Quantitative  Methods  II  

TThheeoorryy    

The  Theory   Script   summarizes   the  whole   theory   of   the   course   in   a   simple   and  

understandable   way.   Concepts   are   explained   with   the   help   of   demonstrative  

examples.  It  is  structured  according  to  the  seven  weeks  of  the  course  and  is  one  

of  the  most  important  parts  of  your  exam  preparation.  Although  practice  is  very  

important,  it  is  even  more  crucial  to  understand  the  basic  concepts  of  the  course  

in  order  to  be  able  to  calculate  and  understand  all  different  kinds  of  exercises  and  

exam  questions.    

   

TTaabbllee    ooff    CCoonntteennttss        

MMaatthheemmaattiiccss     11    

1   Series  of  payments  and  discounting   1  

2   Matrices,  Determinants  and  Systems  of  Equations   6  

3   Linear  Programming   19  

 

SSttaattiissttiiccss     3377    

1   Recap  from  QM1  –  Hypothesis  Testing   37  

2   Statistic  inference  based  on  two  samples   39  

3   Statistic  inference  based  on  more  than  two  samples   48  

4   Simple  Regression   55  

5   Multiple  Regression   63  

6   Regression  assumptions   76  

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Theory  –  Mathematics                          Uniseminar  –  Quantitative  Methods  II    

6  

22         MMaattrriicceess,,    DDeetteerrmmiinnaannttss    aanndd    SSyysstteemmss    ooff    EEqquuaattiioonnss    

This  section  introduces  matrix  algebra,  which  is  in  itself  a  branch  of  mathematics.  

In   general,  matrices   and   their   determinants   can   be   used   to   solve   or   simplify   a  

large  variety  of  problems.  One  of  the  big  applications  is  the  solving  of  systems  of  

linear   equations.   However,   there   are   other   fields   when   you   will   encounter  

matrices   that   are   not   part   of   this   course.   One   example   some   of   you   may  

encounter   in   later   courses   is   that   Econometricians   use   matrices   to   represent  

variables  and  parameters  in  regression  analysis.    

   

22..11         MMaattrriicceess    

WWhhaatt     iiss    aa    mmaattrriixx??    

In  general  a  mmaattrriixx  is  simply  a  rectangular  array  of  numbers.  Thereby  the  order  

of  the  numbers  and  the  format  of  the  matrix  are  important  and  cannot  simply  be  

changed.  The  use  of  matrices  is  that  they  facilitate  many  otherwise  more  difficult  

mathematical  operations.  To  make  this  clear   just  consider   the   following  system  

of  equations:  

𝑎𝑎 𝑥𝑥 + 𝑎𝑎 𝑥𝑥 = 𝑏𝑏  

𝑎𝑎 𝑥𝑥 + 𝑎𝑎 𝑥𝑥 = 𝑏𝑏  

In  matrix  notation  this  can  be  written  as  follows:  

𝐴𝐴𝐴𝐴 = 𝑏𝑏                      𝑤𝑤𝑤𝑤𝑤𝑤ℎ  𝐴𝐴 =𝑎𝑎 𝑎𝑎𝑎𝑎 𝑎𝑎 , 𝑏𝑏 = 𝑏𝑏

𝑏𝑏  𝑎𝑎𝑎𝑎𝑎𝑎  𝑥𝑥 =𝑥𝑥𝑥𝑥  

Thereby,  A   is  a  matrix  of   format  2x2,  while  b  and  x  are  matrices  of   format  2x1.  

Thereby,  the  first  number  always  refers  to  the  row  of  a  matrix,  while  the  second  

refers   to   the  columns.  As  b  and  x  only  have  one  column  they  can  also  be  called  

vectors.  

   

   

   

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Uniseminar  –  Quantitative  Methods  II                                Theory  –  Mathematics    

19  

33     LLiinneeaarr    PPrrooggrraammmmiinngg    

LLiinneeaarr    pprrooggrraammiinngg  attempts  to  optimize  a  linear  function  given  a  linear  set  of  

constraints.   That   means   that   we   need   to   maximize   or   minimize   a   certain  

objective   function,   e.g.   profits   or   costs,   given   a   certain   set   of   constraints,   e.g.  

capacity   constraints   or   demand   constraints.   In   general   there   are   two   ways   to  

solve   such   a   problem.   First,   easy   problems,   which   involve   only   two   decision  

variables,  e.g.  the  production  level  of  two  different  goods,  can  be  solved  with  the  

help  of  a  graph.  Second,  for  more  complex  problems  Excel  needs  to  be  employed  

to  solve  them.  To  do  so,  Excel  does  nothing  else  than  trial  and  error   to   find  the  

optimal  value  of  the  objective  function.  

   

33..11     TThhee    ggrraapphhiiccaall    aapppprrooaacchh    

DDrraawwiinngg    tthhee    sseett    

Whenever   you   like   to   solve   a   problem   via   the   graphical   approach   it   is   best   to  

start   with   the   constraints,   which   define   the   so-­‐called   set.   Only   this   area   is   of  

interest   for   the   optimization   later   on,   as   other   areas   are   ruled   out   by   the  

constraints.  To  show  this,  consider  the  following  example:  

max   3𝑥𝑥 + 4𝑦𝑦  

𝑠𝑠. 𝑡𝑡. : 2𝑥𝑥 + 4𝑦𝑦 ≤ 20  

                 3𝑥𝑥 + 𝑦𝑦 ≤ 9  

                 𝑥𝑥 + 𝑦𝑦 ≥ 2                  𝑥𝑥,𝑦𝑦 ≥ 0  

In   the   problem   we   can   see   three   constraints   subject   to   which   we   need   to  

maximize  the  objective  function.  The  easiest  way  to  draw  these  constraints  is  to  

set  one  of  the  variables  equal  to  zero  to  compute  the  crossing  point  with  one  of  

the  axis  and  then  set  the  other  variable  zero  to  compute  the  crossing  point  with  

the  other  axis.  Let’s  start  with  the  first  constraint:  

2𝑥𝑥 + 4 ∗ 0 = 20             → 𝑖𝑖𝑖𝑖  𝑦𝑦 = 0, 𝑡𝑡ℎ𝑒𝑒𝑒𝑒  𝑥𝑥 = 10  

2 ∗ 0+ 4𝑦𝑦 = 20             → 𝑖𝑖𝑖𝑖  𝑥𝑥 = 0, 𝑡𝑡ℎ𝑒𝑒𝑒𝑒  𝑦𝑦 = 5  

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20  

 

Therefore   we   know   that   the   first   constraint   crosses   the  𝑥𝑥-­‐axis   at  𝑥𝑥 = 10  and  

the  𝑦𝑦 -­‐axis   at  𝑦𝑦 = 5 .   Applying   exactly   the   same   approach   to   the   other   two  

constraints   we   can   produce   the   following   graph.   The   numbers   identify   the  

constraints.   There   is,   however,   one   last   thing   that   needs   to   be  mentioned.   The  

first   two   constraints   are   smaller   equal   constraints,   and   therefore   the   set   is  

constrained   to   the   area   below   them.   The   last   constraint   is   a   greater   equal  

constraint,   which   requires   the   feasible   set   to   lie   above   this   constraint.   The  

feasible  set  is  therefore  the  light  grey  area  beneath  both  the  first  and  the  second  

constraint   and   above   the   third.   On   this   area  we  will   later   try   to  maximize   our  

objective  function.  

   

TThhee    oobbjjeeccttiivvee    ffuunnccttiioonn    

Knowing  the  set,  it  is  now  necessary  to  add  the  oobbjjeeccttiivvee    ffuunnccttiioonn.  Contrary  to  

the  constraints,  however,  the  objective  function  is  not  an  equality  and  therefore  

we   cannot   simply   plug   any   variable   equal   to   zero.   A   first   step   is   to   set   the  

objective  function  equal  to  a  constant  𝑐𝑐:  

3𝑥𝑥 + 4𝑦𝑦 = 𝑐𝑐  

To  be  absolutely  clear,  maximizing  the  objective  function  does  now  mean  finding  

the   largest  possible  value  of  𝑐𝑐,  which  does  not  violate  any  of   the  constraints.  To  

be  able  to  draw  the  objective  function  we  need  to  rewrite  it  in  terms  of  𝑦𝑦:  

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55     MMuullttiippllee    RReeggrreessssiioonn  

Once   you   understood   the   idea   of   a   simple   regression   the   step   to   a   mmuullttiippllee    

rreeggrreessssiioonn  is  not  very  hard.  The  main  change  is  that  more  explanatory  variables  

are  added  to  the  regression  model.  By  doing  this  we  need  to  introduce  some  more  

tests   to   evaluate   the   performance   of   the   model.   Moreover,   there   are   some  

problems  that  can  arise  and  some  new  types  of  variables  that  can  be  introduced.  

   

55..11     TThhee    rreeggrreessssiioonn    eeqquuaattiioonn    

RReeggrreessssiioonn    eeqquuaattiioonnss    ffoorr    tthhee    ppooppuullaattiioonn    

As   just  mentioned  we  can  produce  a  multiple  regression  model  by  adding  more  

explanatory   variables.  Obviously   the   grade   of   student   does  not   only   depend  on  

the  bonus  points,  but  may  also  depend  on  the  subject  he  or  she   is  studying,   the  

gender  or   the  nationality.  Another   impact  might  be  attributed   to   the  amount  of  

study   time   that   is   spent   in   group   learning   rather   than   self-­‐study.   By   adding   all  

these  variables  the  population  regression  model  becomes:  

𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 = 𝛽𝛽 + 𝛽𝛽 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 + 𝛽𝛽 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 + 𝛽𝛽 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 + 𝛽𝛽 𝑓𝑓𝑓𝑓𝑓𝑓𝑐𝑐𝑐𝑐𝑐𝑐 + 𝛽𝛽 𝑔𝑔𝑔𝑔𝑔𝑔 + 𝛽𝛽 𝑜𝑜𝑜𝑜ℎ𝑒𝑒𝑒𝑒

+ 𝛽𝛽 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 + 𝛽𝛽 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔²+ 𝛽𝛽 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 ∗ 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 + 𝜖𝜖  

You  do  not  have  to  worry  if  you  are  unable  to  understand  the  purpose  of  all  these  

variables  by  now.  This  whole  section  will  attempt  to  explain  them  one  by  one.    

   

RReeggrreessssiioonn    eeqquuaattiioonnss    ffoorr    tthhee    ssaammppllee    

Just  as  we  did  in  the  simple  regression  case  we  need  to  take  a  sample  to  estimate  

the  regression  model.  This  results  from  the  fact  that  the  population  is  too  big  to  

be   observed.   Switching   to   the   sample   then   also  means   to   switch   from  Greek   to  

normal  letters:    

𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 = 𝑏𝑏 + 𝑏𝑏 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 + 𝑏𝑏 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 + 𝑏𝑏 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 + 𝑏𝑏 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 + 𝑏𝑏 𝑔𝑔𝑔𝑔𝑔𝑔 + 𝑏𝑏 𝑜𝑜𝑜𝑜ℎ𝑒𝑒𝑒𝑒

+ 𝑏𝑏 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 + 𝑏𝑏 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔²+ 𝑏𝑏 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 ∗ 𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 + 𝑒𝑒    

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64  

Again,   all   those   sample   coefficients   are   just   estimates   for   the   population  

coefficients  and  another  sample  would  result   in  different  coefficients.  Moreover,  

the  last  term  is  still  called  the  residual  and  it  is  on  average  equal  to  zero.  

   

55..22     TThhee    EExxcceell    OOuuttppuutt    

RReeggrreessssiioonn    ssttaattiissttiiccss    

First  of  all  note  that  the  rreeggrreessssiioonn    oouuttppuutt   in  this  section  is  for  our  complete  

model  as  it  is  given  above.  We  will  work  with  this  model  throughout  this  chapter.  

It   is   not   a   problem   if   you   do   not   understand   some   terms   yet,   as   they   will   be  

explained  soon.  The  purpose  of  this  is  simply  to  give  an  overview  of  the  output,  so  

that  you  know  where  to  find  what.    

The  first  row  labeled  mmuullttiippllee    RR  does  not  have  a  very  deep  meaning  in  the  case  

of  a  multiple  regression.   In  a  simple  regression   it  gives   the  correlation  between  

the  dependent  and  the  explanatory  variable.  In  a  multiple  regression  it  is  still  the  

square  root  of  the  R²,  but  does  not  carry  much  intuition.  

 

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76  

66     RReeggrreessssiioonn    aassssuummppttiioonnss  

In  terms  of  the  regression  itself  the  theory  is  so  far  covered.  There  are,  however,  

certain  problems  that  can  arise  with  a  regression  model.  These   then  violate   the  

regression   assumptions.   This   section   attempts   to   name   those   problems   and  

explain  how  to  tackle  them.  One  example  how  to  deal  with  the  problem  of  a  non-­‐

constant   variance   is   the   llooggaarriitthhmmiicc     rreeggrreessssiioonn.   It   uses   the   fact   that   a  

logarithm   can   convert   absolute   in   relative   changes.   Unfortunately,   this   also  

changes  the  interpretation  of  the  coefficient  and  therefore  needs  some  additional  

attention.  

   

66..11     LLiinneeaarriittyy    

HHooww    ttoo    cchheecckk    tthhee    aassssuummppttiioonn    

A   regression   measures   the   linear   relationship   between   variables.   If,   for   any  

reason,  the  relationship  is  not  linear,  then  we  cannot  do  a  linear  regression.  There  

are  two  ways  to  check  the  assumption.  The  first  one  is  to  look  at  all  scatterplots  

between  the  dependent  and  any  explanatory  variable.  If  any  of  these  scatterplots  

shows   a   non-­‐linear   relationship   between   the   variables,   e.g.   a   quadratic  

relationship,  you  got  a  violation.  A  second  approach  is  to  check  the  residual  plots  

for  all  explanatory  variables.  A  non-­‐constant  relationship  between  the  dependent  

and   the   particular   explanatory   variable   would   produce   a   clear   pattern   in   the  

residual  plot.  If  the  residual  plot  looks  like  a  nice  cloud  everything  is  fine.  

   

PPootteennttiiaall    vviioollaattiioonnss    

Some  of  you  might  have  noticed   that  we  already  encountered  a  violation  of   the  

linearity   assumption   just   within   our   model.   Recall   that   we   added   two   group  

terms,  namely  the  simple  group  term  and  a  group²  term.  The  reason  for  this  was  

that  the  group  term  had  a  quadratic  relationship  with  the  grade  variable.  The  first  

way  to  check  this  is  to  produce  a  scatterplot  between  grade  and  group.  Moreover,  

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77  

we   can   also   check   the   residual   plot.   Estimating   a   model   without   the   group²  

variable  leads  to  the  residual  plot  that  is  displayed  on  the  left.  In  that  graph  you  

should  be  able  to  clearly  see  the  quadratic  pattern.  Nevertheless,  by  including  the  

group²  variable  we  can  solve  the  problem  of  non-­‐linearity  as  can  be  seen  from  the  

two  residual  plots  on   the  right.   In   those  graphs   the  pattern   is  gone  because   the  

group²   term   is   able   to   pick   up   the   quadratic   effect.   Therefore,   our   final  model  

does  not  violate  the  linearity  assumption  anymore.  

 

   

66..22     CCoonnssttaanntt    vvaarriiaannccee    

HHooww    ttoo    cchheecckk    tthhee    aassssuummppttiioonn    

Throughout   most   of   the   test   we   use   the   distribution   of   the   error   term.   If   this  

distribution   is   different   for   different   values   of   the   explanatory   variable  we   run  

into   problems   as   the   tests   would   collapse.   It   is   therefore   required   that   the  

variance  of   the  standard  error   is  equal   for  all   levels  of   the  explanatory  variable.  

The  easiest  way  to  check  this  is  to  produce  a  residual  plot  and  check  whether  the  

variance  of  the  residuals  stays  the  same  or  not.  

 

 

 

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Practice

Exams

Extras

Sem

inar

P

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 Practice  Exercises  

   

Quantitative  Methods  II  (IB)  Academic  Year  2011/2012,  Block  3  

       

       

                           

   

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Practice                                    Uniseminar  –  Quantitative  Methods  II  

 

   

PPrraaccttiiccee    EExxeerrcciisseess    

This  part  contains  practice  exercises  to  each  week  and  therefore  to  each  chapter  

of   the   theory   script.   By   this,   you   can   deepen   your   theoretical   knowledge  with  

practical   exercises   and   you   can   go   through   the   exercises   of   these   topics   again,  

which  you  have  not  understood  so  well  until  now.  Although  you  may  think  that  

you   already  have  done   enough   exercises   during   the  weeks,   these   exercises   are  

tailored  specifically  to  your  needs  and  try  to  teach  you  the  most  important  topics  

of  the  exam  in  a  practical  manner.  

   

TTaabbllee    ooff    CCoonntteennttss    

   

MMaatthheemmaattiiccss     11    

  Exercises   1  

  Solutions   27  

 

SSttaattiissttiiccss     8833    

  Exercises   83  

  Solutions   114  

   

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1  

MMaatthheemmaattiiccss    -­‐-­‐    EExxeerrcciisseess    

11     WWeeeekk    11    

SSeerriieess,,    SSeeqquueenncceess,,     IInntteerreesstt    RRaatteess    aanndd    AAnnnnuuiittiieess    

11.. CCaallccuullaattee    tthhee    ffoolllloowwiinngg    ccoommppoouunnddiinngg    pprroobblleemmss    

You  put  5000€  into  your  bank  account  at  an  interest  rate  of  5%  per  year  ii ..

  paid  annually.  

((aa)) What  amount  will  you  have  after  10  years?  

((bb)) How  long  does  it  take  for  the  amount  to  double?  

 

Now  assume  that  this  interest  is  paid  biannually.  

((cc)) What  amount  will  you  have  after  10  years?  

((dd)) How  long  does  it  take  for  the  amount  to  double?  

((ee)) What  is  the  effective  interest  rate  per  year?  

 

How  much  money  should  you  have  invested  5  years  ago  in  order  to  have  ii ii ..

  100,000€  today?  The  interest  rate  is  4%.  

 

The  annual  interest  rate  is  9%.  What  is  the  effective  interest  rate,  if  money  ii iiii ..

  is  compounded  

((ff)) annually?  

((gg)) biannually?  

((hh)) quarterly?  

((ii)) monthly?  

((jj)) continuously?  

 

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Practice     Uniseminar  –  Quantitative  Methods  II  

2  

What   is   the   nominal   interest   rate,   if   the   effective   interest   rate   is   12%  iivv..

  compounded  

((aa)) biannually?  

((bb)) quarterly?  

((cc)) monthly?  

((dd)) continuously?  

 

Your   credit   card   provider   charges   you   1.5%   interest   on   the   outstanding  vv..

  balance   per   month.   What   is   the   effective   annual   rate,   which   you   pay   to  

  your  credit  card  provider?  

 

Assume   that   the   value   of   your   car   depreciates   at   15%   annual   rate  vvii..

  compounded  continuously.    

((ee)) As  compared  to  the  original  value,  what  is  value  of  the  car  after  2  years?  

((ff)) How  long  does  it  take  for  the  car  to  be  worth  25%  of  its  original  value?  

 

What  is  the  present  value  of  5000€  which  you  need  to  pay  in  5  years  time  vviiii ..

  given  that  the  interest  rate  is  5%  

 

22.. CCaallccuullaattee    tthhee    ffoolllloowwiinngg    iinnffiinniittee    ssuummss::    

 ii ..

1 1 1 11 ...3 9 27 81

+ + + + +  

 

 ii ii ..

2 3 4

2 3 4

5 5 5 55 ...8 8 8 8×3 ×3 ×3 ×3+ + + +  

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19  

66     WWeeeekk    66    

LLiinneeaarr    PPrrooggrraammmmiinngg    22    

33.. SSeett     uupp     tthhee     ffoolllloowwiinngg     ll iinneeaarr     pprrooggrraammmmiinngg     pprroobblleemmss,,     aanndd     ssoollvvee    

    tthheemm..    

In  order  to  ensure  safe  operations  at  a  casino,   it  needs  sufficient  security  ii ..

  staff.  Assume  that  the  casino  is  open  24/7.  The  demand  for  security  is  dif-­‐

  ferent   for   each   time   of   day.   Thus,   the   casino   manager   has   divided   each  

  workday   into   6   different   security   requirements.   The   security   staff   re-­‐

  quirements  for  each  shift  are  summarized  in  the  table  below:  

    RReeqquuiirreedd    SSeeccuurriittyy    SSttaaffff    0011::0000    ––    0055::0000     45  

0055::0000    ––    0099::0000     15  0099::0000    ––    1133::0000     40  

1133::0000    ––    1177::0000     55  

1177::0000    ––    2211::0000     90  2211::0000    ––    0011::0000     135  

 

The  manager  wants  to  minimize  the  number  of  security  staff  working  at  the  casi-­‐

no.   The   labor   union   allows   this,   however,   only   under   the   following   two   condi-­‐

tions:  Each  security  officer  can  only  work  8  hours  per  day.  These  8  hours  can  on-­‐

ly  be  worked  consecutively.  (N.B.,  the  6th  and  the  1st  shift  are  consecutive  

((aa)) What  are  the  decision  variables?  

((bb)) What  is  the  objective  Function?  

((cc)) What  are  the  constraints?  

((dd)) What  is  the  optimal  solution?  

 

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20  

AIXonMobyl  produces  kerosene  for  airplanes.  AIXonMobyl  has  3  different  ii ii ..

  production   facilities   (P1,   P2,   P3),  which   it   uses   to   supply  4  different   air-­‐

  ports  (A1,  A2,  A3,  A4).  The  costs  of  1million  gallons  of  Kerosene  from  the  

  production  plants  to  the  airports  is  summarized  in  the  table  below  

  AA11     AA22     AA33     AA44    

PP11     10000   14000   13000   20000  PP22     8000   12000   14000   9000  

PP33     22000   18000   23000   19000    

The  supply  at  each  of  the  production  facilities  looks  as  follows  

PPllaanntt     SSuuppppllyy        ((iinn    mmiillll iioonn    

ggaalllloonnss))    PP11     6000  

PP22     4500  PP33     8000  

 

The  demand  at  each  of  the  airports  looks  as  follows  

AAiirrppoorrtt     SSuuppppllyy        ((iinn    mmiillll iioonn    

ggaalllloonnss))    AA11     1500  AA22     8000  

AA33     2000  

AA44     3000  

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27  

MMaatthheemmaattiiccss    -­‐-­‐    SSoolluuttiioonnss    

11     WWeeeekk    11    

SSeerriieess,,    SSeeqquueenncceess,,     IInntteerreesstt    RRaatteess    aanndd    AAnnnnuuiittiieess    

11.. CCaallccuullaattee    tthhee    ffoolllloowwiinngg    ccoommppoouunnddiinngg    pprroobblleemmss    

You  put  5000€  into  your  bank  account  at  an  interest  rate  of  5%  per  year  ii ..

  paid  annually.  

((aa)) What  amount  will  you  have  after  10  years?  

105000 1.05 8144.47A = × ≈  

 

((bb)) How  long  does  it  take  for  the  amount  to  double?  

10000 5000 1.05 2 1.05 ln 2 ln1.05ln 2ln 2 ln1.05 14.21ln1.05

t t t

t t t

= × ⇔ = ⇔ =

⇔ = × ⇔ = ⇔ ≈  

 

Now  assume  that  this  interest  is  paid  biannually.  

((cc)) What  amount  will  you  have  after  10  years?  

200

.05(1 ) 5000 (1 ) 8193.082

ntt

rA An

= × + = × + ≈  

 

((dd)) How  long  does  it  take  for  the  amount  to  double?  

2A0 = A0 × (1+rn)nt ⇔ 2 = (1+ .05

2)2t ⇔ ln 2

ln1.025= 2t

⇔ ln 22× ln1.025

= t ⇔ t ≈14.04  

 

((ee)) What  is  the  effective  interest  rate  per  year?  

2.05(1 ) (1 )2

neff

rRn

= + −1= + −1= 0.050625  

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28  

How  much  money  should  you  have  invested  5  years  ago  in  order  to  have  ii ii ..

  100000€  today.  The  interest  rate  is  4%  

55

100000100000 1.04 82192.711.04

A A= × ⇔ = ≈  

 

The  annual  interest  rate  is  9%.  What  is  the  effective  interest  rate,  if  money  ii iiii ..

  is  compounded  

((aa)) annually?  

1.09(1 ) 1 (1 ) 1 0.091

neff

rRn

= + − = + − =  

 

((bb)) biannually?  

2.09(1 ) 1 (1 ) 1 0.0920252

neff

rRn

= + − = + − =  

 

((cc)) quarterly?  

4.09(1 ) 1 (1 ) 1 0.09314

neff

rRn

= + − = + − ≈  

 

((dd)) monthly?  

12.09(1 ) 1 (1 ) 1 0.093812

neff

rRn

= + − = + − ≈  

 

((ee)) continuously?  

.091 1 0.09417reffR e e= − = − ≈  

 

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67  

66     WWeeeekk    66    

LLiinneeaarr    PPrrooggrraammmmiinngg    22    

11.. SSeett     uupp     tthhee     ffoolllloowwiinngg     ll iinneeaarr     pprrooggrraammmmiinngg     pprroobblleemmss,,     aanndd     ssoollvvee    

    tthheemm..    

In  order  to  ensure  safe  operations  at  a  casino,   it  needs  sufficient  security  ii ..

  staff.  Assume  that  the  casino  is  open  24/7.  The  demand  for  security  is  dif-­‐

  ferent   for   each   time   of   day.   Thus,   the   casino   manager   has   divided   each  

  workday   into   6   different   security   requirements.   The   security   staff   re-­‐

  quirements  for  each  shift  are  summarized  in  the  table  below:  

    RReeqquuiirreedd    SSeeccuurriittyy    SSttaaffff    0011::0000    ––    0055::0000     45  

0055::0000    ––    0099::0000     15  0099::0000    ––    1133::0000     40  

1133::0000    ––    1177::0000     55  

1177::0000    ––    2211::0000     90  2211::0000    ––    0011::0000     135  

 

The  manager  wants  to  minimize  the  number  of  security  staff  working  at  the  casi-­‐

no.   The   labor   union   allows   this,   however,   only   under   the   following   two   condi-­‐

tions:  Each  security  officer  can  only  work  8  hours  per  day.  These  8  hours  can  on-­‐

ly  be  worked  consecutively.  (N.B.,  the  6th  and  the  1st  shift  are  consecutive  

 

((aa)) What  are  the  decision  variables?  

The  decision  variables  refer  to  the  number  of  security  officers  that  work  in  each  

shift.  Furthermore,  since  every  security  officer  needs  to  work  his  shift  consecu-­‐

tively,   in   an   8   hour   time   period,   the   decision   variables   best   look   as   follows:    

S01_09  (read:  Shift  starting  at  1  ending  at  9)  

S05_13  (read:  Shift  starting  at  5  ending  at  13)  

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68  

S09_17  

S13_21  

S17_01  

S21_05  

 

((bb)) What  is  the  objective  Function?  

The  objective  is  to  minimize  the  total  number  of  security  guards  used  in  a  given  

day.  Thus,  min  S01_09  +  S05_13  +  S09_17  +  S13_21  +  S17_01  +  S21_05  

 

((cc)) What  are  the  constraints?  

 

 

((dd)) What  is  the  optimal  solution?  

 

S01_09 S05_13 S09_17 S13_21 S17_01 S21_05Coefficients 1 1 1 1 1 1 0

Decision  Variables:Requirement  01:00  -­‐  05:00 1 0 >= 45Requirement  05:00  -­‐  13:00 1 1 0 >= 15Requirement  09:00  -­‐  17:00 1 1 0 >= 40Requirement  13:00  -­‐  21:00 1 1 0 >= 55Requirement  17:00  -­‐  01:00 1 1 0 >= 90Requirement  21:00  -­‐  05:00 1 1 0 >= 105

Optimal  Solution

S01_09 S05_13 S09_17 S13_21 S17_01 S21_05Coefficients 1 1 1 1 1 1 205

Decision  Variables: 45 0 40 15 75 30Requirement  01:00  -­‐  05:00 1 45 >= 45Requirement  05:00  -­‐  13:00 1 1 45 >= 15Requirement  09:00  -­‐  17:00 1 1 40 >= 40Requirement  13:00  -­‐  21:00 1 1 55 >= 55Requirement  17:00  -­‐  01:00 1 1 90 >= 90Requirement  21:00  -­‐  05:00 1 1 105 >= 105

Optimal  Solution

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89  

22     WWeeeekk    22    

SSttaattiissttiiccaall     iinnffeerreennccee    bbaasseedd    oonn    mmoorree    tthhaann    ttwwoo    ssaammpplleess    

11.. CCoommppaarriinngg    mmoorree    tthhaann    ttwwoo    ppooppuullaattiioonnss    ooff    qquuaannttiittaattiivvee    ddaattaa    

You  want  to  compare  the  average  speed  of  cars  at  three  different  points  in  ii ..

  your   city.   In   all   of   these  places   the  permitted   speed   is  70km/h,  however  

  you  have  the  feeling  that  drivers  adhere  to  the  speed  limit  differently  at  all  

  three   places.   The   table   below   shows   the   results   of   the   samples   that   you  

  take  at  the  three  different  spots.  

 

((aa)) What  are  the  hypotheses  for  testing  the  scenario  described  above?  

((bb)) Do  the  ANOVA  assumptions  hold?  

((cc)) What  are  SSE,  SST,  SSTO,  MSE  and  MST?  

((dd)) Use  an  F-­‐Test  to  test  the  hypotheses.  

 

P1 P2 P3 OverallMean 72.84 74.96 76.00 74.77Median 73.8 78.1 79.2 73.8Variance 231.32 87.80 95.56 127.03Standard  Deviation 15.21 9.37 9.78 11.27Min 49.2 56.8 57.6 49.2Max 106.6 92.3 93.6 106.6Count 34 52 45 131

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90  

You  are  interested  in  learning  about  the  grades  of  your  fellow  students.  In  ii ii ..

  particular,  you  wonder  on  whether  grades  are  the  same  across  all  different  

  nationalities.  After  sampling,  you  obtain  the  following  numbers:  

 

((aa)) What  are  the  hypotheses  for  testing  the  scenario  described  above?  

((bb)) Do  the  ANOVA  assumptions  hold?  

((cc)) What  are  SSE,  SST,  SSTO,  MSE  and  MST?  

((dd)) Use  an  F-­‐Test  to  test  the  hypotheses  

((ee)) How  much  of  the  differences  in  grades  is  explained  by  the  factor  Nationali-­‐

  ty?  

((ff)) How  do  the  results  differ,   if  you  only  compare  the  grades  of  non-­‐German  

  students?  

 

You  receive  the  following  ANOVA  output  ii iiii ..

 

German Dutch Belgium Other OverallMean 7.00 5.52 6.76 6.29 6.43Median 7 5.5 7 6.5 6.5Variance 3.20 5.42 2.79 5.01 4.38Standard  Deviation 1.79 2.33 1.67 2.24 2.09Min 4 2 4.5 2.5 2Max 10 9.5 9 10 10Count 140 104 60 43 347

Anova:  One  Factor

SUMMARYGroups Count Sum Average Variance

Var1 41 371 9.05 3.55Var2 58 583 … 2.58Var3 44 … 8.00 1.95

ANOVASource  of  Variation SS df MS F P-­‐Value F  Crit

Between  Groups 105.7283 … 52.8641 19.8552 0.0000 3.0608Within  Groups … … …

Total 478.4755 142

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((aa)) What  are  the  missing  values  in  the  table  above?  

 

22.. CCoommppaarriinngg    mmoorree    tthhaann    ttwwoo    ppooppuullaattiioonnss    ooff    ccaatteeggoorriiccaall    ddaattaa    

You  are   interested   in   learning  about   the  market  shares  of   the  top  brands  ii ..

  on  the  German  market.  You  believe  that  VW  with  its  brands  controls  35%,  

  Mercedes   and   related   brands   20%,   Toyota   and   related   brands   15%,   and  

  the  remainder  by  other  brands.  You  take  a  sample  at  a  busy  intersection  in  

  your   home   town,   and   count   the   following   frequencies   for   the   respective  

  brands  

 

((aa)) What  are  the  hypotheses?  

((bb)) Use  a  Chi-­‐Square  test  for  goodness  of  fit  to  test  the  null  hypothesis  

 

You  predict  that  50%  of  students  in  your  year  are  German,  40%  are  Dutch  ii ii ..

  and  10%  are  of  other  nationality.  You  sample  randomly  and  obtain  the  fol-­‐

  lowing  results  

 

((aa)) What  are  the  hypotheses?  

((bb)) Use  a  Chi-­‐Square  test  for  goodness  of  fit  to  test  the  null  hypothesis  

 

A  store  sells  three  different  types  of  tablet  PCs,  type  1,  type  2  and  type  3.  ii iiii ..

  The  store  manager  believes  that  each  of  the  three  types  is  sold  equally  fre-­‐

  quent.  The  store  manager  takes  a  look  at  the  sales  records  for  the  preced-­‐

  ing  month,  and  sees  the  following  numbers  

 

VW Mercedes Toyota Other252 198 162 288

German Dutch Other34 22 12

Type1 Type2 Type3102 109 119

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((aa)) What  are  the  hypotheses?  

((bb)) Use  a  Chi-­‐Square  test  for  goodness  of  fit  to  test  the  null  hypothesis  

 

You  wonder  whether  the  color  of  a  car  is  dependent  on  the  gender  of  the  iivv..

  driver.  You  observe  the  following  numbers:  

 

((aa)) What  are  the  hypotheses?  

((bb)) Use  a  Chi-­‐Square  test  for  independence  to  test  the  null  hypothesis  

 

An  online  retailer  is  interested  in  learning  more  about  its  customers’  shop-­‐vv..

  ping  behaviors.   In   a   first   analysis,   they   classify   their   customers   into   first  

  time  customers  and  repeat  customers.  The  retailer  sells  products  in  three  

  different  categories.  Shoes,  attire  and  accessories.  Of  the  60  new  customers  

  buying  at  the  retailer  last  month,  13  bought  shoes,  17  bought  attire,  and  30  

  bought  accessories.  Of  the  420  purchases  of  repeat  customers,  100  bought  

  shoes,  220  bought  attire  and  200  bought  accessories.  

((aa)) Set  up  a  contingency  table.  

((bb)) Use   a   Chi-­‐Square   test   for   independence   to   test   whether   the   category   of  

  product  purchases  is  independent  of  customer  status.  

     

Black Green RedMale 103 80 25

Female 20 14 15

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133  

33     WWeeeekk    33    

SSiimmppllee    RReeggrreessssiioonn    

11.. TThhee    rreeggrreessssiioonn    eeqquuaattiioonn    

Before  a  new  movie  comes  out,  a  trailer  is  usually  released  way  in  advance.  While  

the   platform   TFMP   does   not   have   the   function   of   rating   movie   trailers,  

Youtube.com  does  provide  this  feature.  There,  you  can  rate  any  video  with  0  –  5  

stars.  You  wonder,  whether  the  Youtube  trailer  rating  of  a  movie  is  predicting  the  

final  rating  of  a  movie  on  the  TFMP  platform.  This,  you  want  to  examine  with  the  

following  regression  model:  

0 1 _ rat t ratβ β ε= + +  

 

Use  the  five  observations  to  estimate   0β and   1β  ii ..

((aa)) Plot  the  values  in  a  plain  

((bb)) Draw  the  best  fitting  line  through  the  plain  

 

rat t_rat8 3.57 4

9.5 44.5 15.5 2.5

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134  

((cc)) Find   the  equation  of   the  best   fitting   line  (remember,  b0   is  your  best  esti-­‐

  mate  of   0β and  b1  is  your  best  estimate  of   1β )  

Remember,  we  are  trying  to  find  the  coefficients  of  the  “best  fitting  line”.  As  you  

will  remember  from  your  QM1  lecture,  you  need  to  minimize  the  sum  of  squared  

residuals.   The   residual   is   defined   as:   .   This   reads:   the   difference   be-­‐

tween  the  observed  value,   ,  and  the  predicted  value,   .  While  it  would  be  bur-­‐

densome  to  write  out  the  entire  sum  of  the  squared  residuals,  you  might  remem-­‐

ber  that  there  is  a  shortcut  to  estimate  the  coefficients:  

 and    

Thus,  to  use  both  equations,  we  first  need  to  determine    and   :  

Simple  math  will  give  you   .  

Next,  you  can  determine  b1  and  b0.  

 

and    

 

 

Determine  the  R²  ii ii ..

R²   is   the   ratio  between   the  explained  variation   and   the   total   variation.   The   ex-­‐

plained   variation   is   the   difference   between   the   sum   of   square   differences   be-­‐

tween  the  predicted  value,   ,  and  the  observed  value,   .  The  total  variation   is  

ˆi i iy yε = −

iy ˆiy

11

2

1

( )( )

( )

n

i iiXY

nXX

ii

x x y ySSbSS x x

=

=

− −= =

∑0 1b y b x= −

x y

3.06.9

xy==

11

2

1

2 2 2 2 2

( )( )

( )

(3.5 3)(8 6.9) (4 3)(7 6.9) (4 3)(9.5 6.9) (1 3)(4.5 6.9) (2.5 3)(5.5 6.9)(3.5 3) (4 3) (4 3) (1 3) (2.5 3)

1.3462

n

i iiXY

nXX

ii

x x y ySSbSS x x

=

=

− −= =

− − + − − + − − + − − + − −=− + − + − + − + −

0 6.9 1.3462 3 2.8615b = − × =

ˆiy iy

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the  sum  of  square  differences  between  the  average  value  of  the  dependent  varia-­‐

ble,   ,  and  each  individual  observation,   .    

Thus,  the  explained  variation  is  

 

and  the  total  variation:  

 

Thus,    

 

According  to   the  5  observations,   the  explanatory  variable   t_rat  explains  75%  of  

the  change  in  the  dependent  variable  rat.  

 

Based  on  your  model,  which   rating  would  you  expect   for   a  movie  whose  ii iiii ..

  trailer  has  a  rating  of  3.5?    

 

Plugging  in  3.5  for  t_rat  would  yield:  

 

   

y iy

2

12 2 2

2 2

ˆ( )

(2.8615 1.3462*3.5 6.9) (2.8615 1.3462*4 6.9) (2.8615 1.3462*4 6.9)(2.8615 1.3462*1 6.9) (2.8615 1.3462*2.5 6.9) 11.7788

n

ii

SST y y=

= − =

+ − + + − + + − ++ − + + − =

2 2 2 2 2 2

1( ) (8 6.9) (7 6.9) (9.5 6.9) (4.5 6.9) (5.5 6.9) 15.70

n

ii

SSTO y y=

= − = − + − + − + − + − =∑

2 11.7788 0.75015.70

SSTRSSTO

= = =

∂ 2.862 1.346 _rat t rat= +

∂ 2.862 1.346 3.5 7.573rat = + × =

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Extras

Sem

inar

E Exams

Extras

Sem

inar

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 Exams  

   

Quantitative  Methods  II  (IB)  Academic  Year  2010/2011,  Block  3  

     

 

     

                                   

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Exams                          Uniseminar  –  Quantitative  Methods  II  

 

EExxaammss    

You  should  start  early  with  the  calculation  of  exams,  because  you  need  to  get  a  

general   feeling   of   how   the   exams   are   built   up.   You  will   soon  discover   how   the  

exams  are  constructed  and  that  there  are  general  tendencies,  which  repeat  from  

exam  to  exam.  In  this  part  you  will  find  old  exams  of  the  Maastricht  University,  as  

well  as  one  practice  exams  constructed  by  Uniseminar.  During  the  seminar  you  

will  then  receive  a  further  practice  exam.  

   

TTaabbllee    ooff    CCoonntteennttss    

   

PPrraaccttiiccee    EExxaamm    11    ((iinnccll ..    ssoolluuttiioonnss))     11    

       

OOlldd    EExxaammss     3333    

  10/11  Resit  

  10/11  First  Sit  

  09/10  Resit  

  09/10  First  Sit  

  08/09  Resit  

  08/09  First  Sit  

 

 

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Uniseminar  –  Quantitative  Methods  II     Practice  Exam  1    

1  

MMaatthheemmaattiiccss    

 

11..))  What  is  the  value  of  the  following  infinite  series?  

2+32−34 +

38 −

316 +

332 +⋯  

a.) 2.50  

b.) 2.75  

c.) 3.00  

d.) 3.25  

 

22..)) Consider  the  following  series  of  payments.  Today  you  receive  200€,  in  one  

year  you  receive  400€,  in  two  years  again  200€,  in  three  years  again  400€,  

in   four  years  again  200€  and  so  on.  The  project  ends  after  thirteen  years  

and  the  yearly  interest  rate  is  5%.  What  is  the  present  value  of  this  series  

of  payments?  

a.) between  3000  and  3100  

b.) between  3100  and  3200    

c.) between  3200  and  3300  

d.) between  3300  and  3400  

 

33..)) Consider  the  following  investment  opportunity:  You  are  offered  a  payment  

of  200€  right  now  and  a  second  payment  of  200€  next  year.  However,  to  

get  those  payments  you  have  to  pay  410€  in  two  years  from  now.  What  is  

the  internal  rate  of  return  of  this  project?  

a.) 2.8  %  

b.) 1.6  %.  

c.) 9.4  %  

d.) 11.2  %  

 

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Practice  Exam  1                                        Uniseminar  –  Quantitative  Methods  II      

2  

44..)) Consider  the  following  three  matrixes:  A  is  of  format  m  x  n,  B  is  format  k  x  l  

and  C  is  of  format  p  x  q.  When  is  the  following  defined:  𝐴𝐴 ∗ 𝐵𝐵 + 𝐶𝐶?  

a.) 𝑘𝑘 = 𝑙𝑙 = 𝑚𝑚 = 𝑞𝑞  and  𝑛𝑛 = 𝑝𝑝  

b.) 𝑘𝑘 = 𝑙𝑙  and  𝑚𝑚 = 𝑛𝑛 = 𝑝𝑝 = 𝑞𝑞  

c.) 𝑘𝑘 = 𝑙𝑙 = 𝑚𝑚 = 𝑝𝑝  and  𝑛𝑛 = 𝑞𝑞  

d.) 𝑘𝑘 = 𝑙𝑙 = 𝑝𝑝 = 𝑞𝑞  and  𝑚𝑚 = 𝑛𝑛  

   

 

55..))  Consider  the  following  invertible  matrix:  

 𝐴𝐴 =1 2 11 1 02 2 1

 

The  sseeccoonndd  column  of  the  inverse  𝐴𝐴  is  given  as  2𝑥𝑥𝑥𝑥

 

What  are  the  values  of  𝑥𝑥  and  𝑥𝑥 ?  

a.) 𝑥𝑥 = 1, 𝑥𝑥 = 0  

b.) 𝑥𝑥 = −1, 𝑥𝑥 = 0  

c.) 𝑥𝑥 = 0, 𝑥𝑥 = 1  

d.) 𝑥𝑥 = 0, 𝑥𝑥 = −1  

 

 

66..)) Consider  the  following  matrix  𝐴𝐴 = 1 1𝑏𝑏 𝑎𝑎² .  It  only  has  an  inverse  if…  

a.) 𝑎𝑎 ≠ 𝑏𝑏  

b.) 𝑎𝑎 = −𝑏𝑏  

c.) 𝑎𝑎 = 𝑏𝑏  and  𝑎𝑎 = −𝑏𝑏  

d.) 𝑎𝑎 ≠ 𝑏𝑏  and  𝑎𝑎 ≠ −𝑏𝑏  

   

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Uniseminar  –  Quantitative  Methods  II     Practice  Exam  1    

3  

77..)) When  can  we  be  absolutely  sure  that  a  certain  matrix  𝐴𝐴  is  invertible?  

I.)  There  exists  a  matrix  𝐵𝐵  such  that   𝐴𝐴𝐴𝐴 = 0  

II.)  The  system  of  equations  𝐴𝐴𝐴𝐴 = 𝑏𝑏  has  a  unique  solution  

 

a.) In  I.)  we  can  be  sure,  in  II.)  not  

b.) In  II.)  we  can  be  sure,  in  I.)  not  

c.) In  both  cases  we  can  be  sure  

d.) Neither  in  I.)  nor  in  II.)  can  we  be  sure  

 

 

88..)) The  determinant  of   the  3x3  matrix  A   is  equal   to  4.  First,  we  multiply   the  

first  row  of  A  with  4.  Second,  we  multiply  the  second  column  of  A  with  3.  

Finally,  we  multiply  all  elements  of  A  with  2.  What  will  the  determinant  of  

this  new  matrix  be  equal  to?  

a.) 384  

b.) 96  

c.) 192  

d.) 48  

 

 

99..))  The   system  𝐴𝐴𝐴𝐴 = 𝑏𝑏   has   a   unique   solution.  What   can   you   say   about   the  

solutions  of  the  system  𝐴𝐴𝐴𝐴 = 𝑐𝑐?  

a.) The  system  will  have  no  solution  

b.) The  system  will  have  infinitely  many  solutions  

c.) The  system  will  have  a  unique  solution  

d.) Nothing  can  be  said  on  the  basis  of  the  given  information  

 

 

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Practice  Exam  1                                        Uniseminar  –  Quantitative  Methods  II      

10  

SSttaattiissttiiccss    

This   trial   exam   is   based   on   a   dataset   that   contains   315   students.   Of   these  

students   multiple   characteristics   like   the   QM1   grade,   the   gender   or   the  

nationality,  etc.  are  collected.  The  variables  are  named  as  follows:  

ggrraaddee     QM1  grade  of  a  student  on  a  scale  from  0  to  10,  where  10  is  best  

bboonnuuss     The  bonus  points  a  student  got  for  the  QM1  exam  on  a  scale  from  0  

    to  8  

mmaallee       A  gender  dummy,  1  for  male  and  0  for  female  students  

IIBB       dummy:  1  for  IB  students,  0  otherwise  

EEccoonn       dummy:  1  for  Economics  students,  0  otherwise  

FFiissccaall     dummy:  1  for  Fiscal  Economics  students,  0  otherwise  

 

Some  people  claim  that   the  performance   in  a  QM1  exam  does  solely  depend  on  

the  level  of  mathematical  and  statistical  talent.  If  this  claim  was  true  this  would  

mean   that   the   QM1   score   of   a   student   must   be   equal   to   the   QM2   score   of   a  

student.  

 

2211..)) Which  test  can  be  used  to  evaluate  this  claim?  

 

a.) A  Chi-­‐Square  test  for  Independence  to  check  for  the  relationship  between  

talent  and  QM  scores  

b.) A  two  sample  t-­‐test  for  QM1  and  QM2  scores  

c.) A  paired  sample  t-­‐test  for  the  difference  in  QM1  and  QM2  grades  

d.) ANOVA  with  the  students  as  the  levels  and  the  QM  scores  as  the  response  

 

Forget  about  the  claim  and  focus  on  something  different.  Some  people  claim  that  

male  and  female  students  are  not  equally  successful  in  QM1.  Unfortunately,   it   is  

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Uniseminar  –  Quantitative  Methods  II     Practice  Exam  1    

11  

not  clear  yet  who  of  the  two  actually  performs  better.  Therefore  we  could  test  the  

following  set  of  hypothesis  about  the  mean  difference  in  the  QM1  bonus  scores  of  

female  and  male  students.  

𝐻𝐻 : 𝜇𝜇 − 𝜇𝜇 = 0                                                    𝐻𝐻 : 𝜇𝜇 − 𝜇𝜇 ≠ 0  

2222..)) To   test   this   claim,   consider   the   descriptive   statistics   table   on   the   right.  

Against  the  state  alternative,  the  p-­‐value  is...  

 

a.) between  5%  and  10%.  

b.) between  2.5%  and  5%.  

c.) between  1%  and  2.5%.  

d.) smaller  than  1%.  

 

Obviously  gender  is  not  the  only  characteristic  that  impacts  the  grade.  Even  more  

academic   discussion   focuses   on   the   difference   in   the   performance   of   IB,  

Economics  and  Fiscal  Economics  students.  With  the  help  of  a  one  way  ANOVA  we  

can  test  the  following  hypothesis:  

𝐻𝐻 : 𝜇𝜇 = 𝜇𝜇 = 𝜇𝜇  

The  results  of  this  ANOVA  test  are  given  in  the  Excel  report.  

 

2233..)) Which  of  the  following  is  nnoott  true  for  this  ANOVA  test?  

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Extras

Sem

inar

E

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 Extras  

   

Quantitative  Methods  II  (IB)  Academic  Year  2011/2012,  Block  3  

       

   

 

 

 

 

 

 

 

 

   

   

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Extras       Uniseminar  –  Quantitative  Methods  II  

 

EExxttrraass    

In   this   part   you   find   several   extras   that   will   be   very   helpful   for   your   exam  

preparation.   In  this  course  you  will   find  an  extra  explanation  of  how  to  read-­‐off  

the  critical  values  of  the  statistics  tables  and  the  formula  sheets  for  math  as  well  

as  statistics.  We  decided  to  give  you  the  original   formula  sheets,  which  you  will  

also   have   during   your   exam,   as   it   is   essential   to   get   used   to   the   exam’s  

circumstances.   However   during   the   seminar   the   tutor   will   discuss   the   formula  

sheets  and  will  highlight  or  extend  several  sections.  

   

TTaabbllee    ooff    CCoonntteennttss    

   

FFoorrmmuullaa    SShheeeettss     11    

   

HHooww    ttoo    rreeaadd    ssttaattiissttiiccss    ttaabblleess     99    

     

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Uniseminar  –  Quantitative  Methods  II                                      Extras  

9  

HHooww    ttoo    rreeaadd    tthhee    SSttaattiissttiiccss    ttaabblleess    

zz-­‐-­‐ttaabbllee    

The   𝑧𝑧-­‐scores   are   given   on   the   outside   of   the   table.   The   numbers   in   the   inside  correspond  to  the  area  under  the  curve,  which  represents  the  probability.  

 

 

 

 

zz     00..0000     00..0011     00..0022     00..0033     00..0044     00..0055     00..0066     00..0077     00..0088     00..0099    00..00     0.5000   0.5040   0.5080   0.5120   0.5160   0.5199   0.5239   0.5279   0.5319   0.5359  00..11     0.5398   0.5438   0.5478   0.5517   0.5557   0.5596   0.5636   0.5675   0.5714   0.5753  00..22     0.5793   0.5832   0.5871   0.5910   0.5948   0.5987   0.6026   0.6064   0.6103   0.6141  00..33     0.6179   0.6217   0.6255   0.6293   0.6331   0.6368   0.6406   0.6443   0.6480   0.6517  00..44     0.6554   0.6591   0.6628   0.6664   0.6700   0.6736   0.6772   0.6808   0.6844   0.6879  00..55     0.6915   0.6950   0.6985   0.7019   0.7054   0.7088   0.7123   0.7157   0.7190   0.7224  00..66     0.7257   0.7291   0.7324   0.7357   0.7389   0.7422   0.7454   0.7486   0.7517   0.7549  00..77     0.7580   0.7611   0.7642   0.7673   0.7704   0.7734   0.7764   0.7794   0.7823   0.7852  00..88     0.7881   0.7910   0.7939   0.7967   0.7995   0.8023   0.8051   0.8078   0.8106   0.8133  00..99     0.8159   0.8186   0.8212   0.8238   0.8264   0.8289   0.8315   0.8340   0.8365   0.8389  11..00     0.8413   0.8438   0.8461   0.8485   0.8508   0.8531   0.8554   0.8577   0.8599   0.8621  11..11     0.8643   0.8665   0.8686   0.8708   0.8729   0.8749   0.8770   0.8790   0.8810   0.8830  11..22     0.8849   0.8869   0.8888   0.8907   0.8925   0.8944   0.8962   0.8980   0.8997   0.9015  11..33     0.9032   0.9049   0.9066   0.9082   0.9099   0.9115   0.9131   0.9147   0.9162   0.9177  11..44     0.9192   0.9207   0.9222   0.9236   0.9251   0.9265   0.9279   0.9292   0.9306   0.9319  11..55     0.9332   0.9345   0.9357   0.9370   0.9382   0.9394   0.9406   0.9418   0.9429   0.9441  11..66     0.9452   0.9463   0.9474   0.9484   0.9495   0.9505   0.9515   0.9525   0.9535   0.9545  11..77     0.9554   0.9564   0.9573   0.9582   0.9591   0.9599   0.9608   0.9616   0.9625   0.9633  11..88     0.9641   0.9649   0.9656   0.9664   0.9671   0.9678   0.9686   0.9693   0.9699   0.9706  11..99     0.9713   0.9719   0.9726   0.9732   0.9738   0.9744   0.9750   0.9756   0.9761   0.9767  22..00     0.9772   0.9778   0.9783   0.9788   0.9793   0.9798   0.9803   0.9808   0.9812   0.9817  22..11     0.9821   0.9826   0.9830   0.9834   0.9838   0.9842   0.9846   0.9850   0.9854   0.9857  22..22     0.9861   0.9864   0.9868   0.9871   0.9875   0.9878   0.9881   0.9884   0.9887   0.9890  22..33     0.9893   0.9896   0.9898   0.9901   0.9904   0.9906   0.9909   0.9911   0.9913   0.9916  22..44     0.9918   0.9920   0.9922   0.9925   0.9927   0.9929   0.9931   0.9932   0.9934   0.9936  22..55     0.9938   0.9940   0.9941   0.9943   0.9945   0.9946   0.9948   0.9949   0.9951   0.9952  22..66     0.9953   0.9955   0.9956   0.9957   0.9959   0.9960   0.9961   0.9962   0.9963   0.9964  22..77     0.9965   0.9966   0.9967   0.9968   0.9969   0.9970   0.9971   0.9972   0.9973   0.9974  22..88     0.9974   0.9975   0.9976   0.9977   0.9977   0.9978   0.9979   0.9979   0.9980   0.9981  22..99     0.9981   0.9982   0.9982   0.9983   0.9984   0.9984   0.9985   0.9985   0.9986   0.9986  33..00     0.9987   0.9987   0.9987   0.9988   0.9988   0.9989   0.9989   0.9989   0.9990   0.9990  

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