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Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf ·...

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Economics 172 Issues in African Economic Development Professor Ted Miguel Department of Economics University of California, Berkeley
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Page 1: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Econ

omic

s 17

2Is

sues

in A

frica

n E

cono

mic

Dev

elop

men

t

Pro

fess

or T

ed M

igue

lD

epar

tmen

t of E

cono

mic

sU

nive

rsity

of C

alifo

rnia

, Ber

kele

y

Page 2: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Econ

omic

s 17

2Is

sues

in A

frica

n E

cono

mic

Dev

elop

men

t

Lect

ure

17 �

Mar

ch 1

3, 2

007

Page 3: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

3

�Th

e m

idte

rm e

xam

is th

is T

hurs

day

Mar

ch 1

5th

in c

lass

Page 4: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

4

�Th

e m

idte

rm e

xam

is th

is T

hurs

day

Mar

ch 1

5th

in c

lass

�R

eade

r #2

avai

labl

e in

Cop

y C

entra

l lat

er th

is w

eek

Page 5: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

5

The

regr

essi

on d

isco

ntin

uity

(RD

) app

roac

h

�C

lear

ly c

ompa

ring

scho

lars

hip

win

ners

to s

chol

arsh

ip

lose

rs is

not

a v

ery

appe

alin

g st

rate

gy: t

he w

inne

rs a

re

muc

h be

tter s

tude

nts,

so

lose

rs a

re n

ot a

goo

d �c

ompa

rison

gro

up�

Page 6: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

6

2001

exa

m

scor

e

Edu

catio

nal

atta

inm

ent

2005

-200

6 (y

rs)

GS

P w

inne

rsG

SP

lose

rs

Sco

re*

Page 7: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

7

The

regr

essi

on d

isco

ntin

uity

(RD

) app

roac

h

�C

lear

ly c

ompa

ring

scho

lars

hip

win

ners

to s

chol

arsh

ip

lose

rs is

not

a v

ery

appe

alin

g st

rate

gy: t

he w

inne

rs a

re

muc

h be

tter s

tude

nts,

so

lose

rs a

re n

ot a

goo

d �c

ompa

rison

gro

up�

�O

ne w

ay to

get

aro

und

this

is to

focu

s on

stu

dent

s �v

ery

clos

e to

�the

win

ning

thre

shol

d te

st s

core

leve

l

Page 8: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

8

2001

exa

m

scor

e

Edu

catio

nal

atta

inm

ent

2005

-200

6 (y

rs)

GS

P w

inne

rsG

SP

lose

rs

Sco

re*

Page 9: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

9

The

regr

essi

on d

isco

ntin

uity

(RD

) app

roac

h

�C

lear

ly c

ompa

ring

scho

lars

hip

win

ners

to s

chol

arsh

ip

lose

rs is

not

a v

ery

appe

alin

g st

rate

gy: t

he w

inne

rs a

re

muc

h be

tter s

tude

nts,

so

lose

rs a

re n

ot a

goo

d �c

ompa

rison

gro

up�

�O

ne w

ay to

get

aro

und

this

is to

focu

s on

stu

dent

s �v

ery

clos

e to

�the

win

ning

thre

shol

d te

st s

core

leve

l

�In

the

limit,

com

parin

g th

e st

uden

t who

just

bar

ely

won

(r

ecei

ving

Sco

re*)

to th

e st

uden

t who

just

bar

ely

lost

(S

core

* �

ε) s

houl

d yi

eld

a co

mpa

rison

gro

up o

f los

ers

alm

ost i

dent

ical

to w

inne

rs a

long

uno

bser

vabl

es, t

oo

Page 10: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

10

2001

exa

m

scor

e

Edu

catio

nal

atta

inm

ent

2005

-200

6 (y

rs)

GS

P w

inne

rs (T

i=1)

GS

P lo

sers

(Ti=

0)

Sco

re*

RD

est

imat

e of

the

impa

ct o

f win

ning

Page 11: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

11

Trea

tmen

t effe

cts

and

omitt

ed v

aria

ble

bias

(1)

Yi=

a +

bT i

+ cX

i+

e i

(2)

E(Y

i| T

i=1)

�E

(Yi|

Ti=

0)

= [a

+ b

+ c

E(X

i| T

i=1)

+ E

(ei|

Ti=

1)]

�[a

+ 0

+ c

E(X

i| T

i=0)

+ E

(ei|

Ti=

0)]

= b

+ c

[E(X

i| T

i=1)

�E

(Xi|

Ti=

0)]

True

effe

ct�O

mitt

ed v

aria

ble/

sele

ctio

n bi

as� t

erm

Page 12: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

12

Trea

tmen

t effe

cts

and

omitt

ed v

aria

ble

bias

(2)

E(Y

i| T

i=1)

�E

(Yi|

Ti=

0)=

b+

c [E

(Xi|

Ti=

1) �

E(X

i| T

i=0)

]

Ass

ume

that

any

rele

vant

om

itted

var

iabl

es v

ary

�sm

ooth

ly�,

so v

ery

little

, with

resp

ect t

o th

e te

st s

core

, an

d do

not

�jum

p� a

cros

s th

e w

inni

ng th

resh

old:

Page 13: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

13

Trea

tmen

t effe

cts

and

omitt

ed v

aria

ble

bias

(2)

E(Y

i| T

i=1)

�E

(Yi|

Ti=

0)=

b+

c [E

(Xi|

Ti=

1) �

E(X

i| T

i=0)

]

Ass

ume

that

any

rele

vant

om

itted

var

iabl

es v

ary

�sm

ooth

ly�,

so v

ery

little

, with

resp

ect t

o th

e te

st s

core

, an

d do

not

�jum

p� a

cros

s th

e w

inni

ng th

resh

old:

= b

+ c

[ (x*

+ δ

) �x*

]=

b+

c*δ

≈b

Page 14: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

14

Usi

ng th

e R

D a

ppro

ach

�M

ore

gene

rally

RD

met

hods

can

be

used

whe

neve

r pr

ogra

m /

treat

men

t ass

ignm

ent h

as a

�sha

rp

disc

ontin

uity

�, in

oth

er w

ords

, a v

ery

rapi

d ch

ange

in

the

likel

ihoo

d of

ass

ignm

ent w

ith re

spec

t to

an

unde

rlyin

g �s

moo

th�v

aria

ble

(her

e, th

e te

st s

core

)

Page 15: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

15

Usi

ng th

e R

D a

ppro

ach

�M

ore

gene

rally

RD

met

hods

can

be

used

whe

neve

r pr

ogra

m /

treat

men

t ass

ignm

ent h

as a

�sha

rp

disc

ontin

uity

�, in

oth

er w

ords

, a v

ery

rapi

d ch

ange

in

the

likel

ihoo

d of

ass

ignm

ent w

ith re

spec

t to

an

unde

rlyin

g �s

moo

th�v

aria

ble

(her

e, th

e te

st s

core

)

�Fo

r exa

mpl

e, p

eopl

e m

ay o

nly

get a

loan

if th

eir c

redi

t sc

ore

is s

uffic

ient

ly h

igh.

If y

ou c

ompa

re p

eopl

e w

ith,

say,

a c

redi

t sco

re o

f 750

ver

sus

with

749

they

are

ve

ry s

imila

r, bu

t onl

y th

e fo

rmer

gro

up g

ets

a lo

an

Page 16: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

16

Usi

ng th

e R

D a

ppro

ach

�M

ore

gene

rally

RD

met

hods

can

be

used

whe

neve

r pr

ogra

m /

treat

men

t ass

ignm

ent h

as a

�sha

rp

disc

ontin

uity

�, in

oth

er w

ords

, a v

ery

rapi

d ch

ange

in

the

likel

ihoo

d of

ass

ignm

ent w

ith re

spec

t to

an

unde

rlyin

g �s

moo

th�v

aria

ble

(her

e, th

e te

st s

core

)

�Fo

r exa

mpl

e, p

eopl

e m

ay o

nly

get a

loan

if th

eir c

redi

t sc

ore

is s

uffic

ient

ly h

igh.

If y

ou c

ompa

re p

eopl

e w

ith,

say,

a c

redi

t sco

re o

f 750

ver

sus

with

749

they

are

ve

ry s

imila

r, bu

t onl

y th

e fo

rmer

gro

up g

ets

a lo

an

�R

D L

imita

tion:

�loc

al�t

reat

men

t effe

ct a

t the

thre

shol

d

Page 17: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

17

Em

piric

al m

etho

ds s

o fa

r in

the

cour

se

�A

fund

amen

tal e

cono

met

ric c

once

rn in

em

piric

al

econ

omic

rese

arch

: non

-ran

dom

sel

ectio

n in

to

�trea

tmen

t�/ o

mitt

ed v

aria

ble

bias

(OV

B)

�P

oten

tial s

olut

ions

:

Page 18: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

18

Em

piric

al m

etho

ds s

o fa

r in

the

cour

se

�A

fund

amen

tal e

cono

met

ric c

once

rn in

em

piric

al

econ

omic

rese

arch

: non

-ran

dom

sel

ectio

n in

to

�trea

tmen

t�/ o

mitt

ed v

aria

ble

bias

(OV

B)

�P

oten

tial s

olut

ions

:(1

) Con

trol f

or a

ll re

leva

nt fa

ctor

s (c

halle

ngin

g!)

(2) R

ando

miz

ed e

valu

atio

n

Page 19: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

19

Em

piric

al m

etho

ds s

o fa

r in

the

cour

se

�A

fund

amen

tal e

cono

met

ric c

once

rn in

em

piric

al

econ

omic

rese

arch

: non

-ran

dom

sel

ectio

n in

to

�trea

tmen

t�/ o

mitt

ed v

aria

ble

bias

(OV

B)

�P

oten

tial s

olut

ions

:(1

) Con

trol f

or a

ll re

leva

nt fa

ctor

s (c

halle

ngin

g!)

(2) R

ando

miz

ed e

valu

atio

n(3

) Diff

eren

ce in

diff

eren

ces

(DD

)(4

) Reg

ress

ion

disc

ontin

uity

(RD

)

Page 20: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

20

Em

piric

al m

etho

ds s

o fa

r in

the

cour

se

�A

fund

amen

tal e

cono

met

ric c

once

rn in

em

piric

al

econ

omic

rese

arch

: non

-ran

dom

sel

ectio

n in

to

�trea

tmen

t�/ o

mitt

ed v

aria

ble

bias

(OV

B)

�P

oten

tial s

olut

ions

:(1

) Con

trol f

or a

ll re

leva

nt fa

ctor

s (c

halle

ngin

g!)

(2) R

ando

miz

ed e

valu

atio

n(3

) Diff

eren

ce in

diff

eren

ces

(DD

)(4

) Reg

ress

ion

disc

ontin

uity

(RD

)

�E

ach

of th

ese

met

hods

has

thei

r ow

n st

reng

ths

and

limita

tions

, alth

ough

if a

rand

omiz

ed e

xper

imen

t is

poss

ible

, it i

s us

ually

thou

ght o

f as

the

gold

sta

ndar

d

Page 21: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

21

Theo

retic

al m

odel

s so

far i

n th

e co

urse

�Th

e S

olow

Gro

wth

Mod

el

�S

exua

l beh

avio

r and

HIV

risk

Page 22: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

22

Theo

retic

al m

odel

s so

far i

n th

e co

urse

�Th

e S

olow

Gro

wth

Mod

el

�S

exua

l beh

avio

r and

HIV

risk

�W

ithin

hou

seho

ld a

lloca

tion

unde

r ext

rem

e sc

arci

ty

�E

duca

tiona

l inv

estm

ent,

time

horiz

ons,

and

gen

der

Page 23: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

23

Mai

n su

bsta

ntiv

e to

pics

so

far i

n th

e co

urse

�P

atte

rns

of A

frica

n ec

onom

ic d

evel

opm

ent

�Th

eorie

s of

eco

nom

ic g

row

th

�G

eogr

aphy

, hea

lth, a

nd d

evel

opm

ent

Page 24: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

24

Mai

n su

bsta

ntiv

e to

pics

so

far i

n th

e co

urse

�P

atte

rns

of A

frica

n ec

onom

ic d

evel

opm

ent

�Th

eorie

s of

eco

nom

ic g

row

th

�G

eogr

aphy

, hea

lth, a

nd d

evel

opm

ent

�Th

e ec

onom

ics

of H

IV/A

IDS

�E

cono

mic

sho

cks

and

rura

l hou

seho

lds

�H

uman

cap

ital

Page 25: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

25

Nex

t top

ic: e

nviro

nmen

tal a

nd d

evel

opm

ent

�W

hat w

ill h

appe

n to

Afri

ca a

s a

resu

lt of

clim

ate

chan

ge?

Wha

t if g

loba

l tem

pera

ture

s ke

ep ri

sing

?

�O

ne im

porta

nt is

sue

is w

ater

sca

rcity

, if t

empe

ratu

res

rise

and

drou

ghts

bec

ome

mor

e co

mm

on

Page 26: Economics 172 - University of California, Berkeleywebfac/emiguel/e172_s07/lecture17.pdf · Economics 172 Issues in African Economic Development Professor Ted Miguel Department of

Eco

nom

ics

172:

Lec

ture

17

26

Nex

t top

ic: e

nviro

nmen

tal a

nd d

evel

opm

ent

�W

hat w

ill h

appe

n to

Afri

ca a

s a

resu

lt of

clim

ate

chan

ge?

Wha

t if g

loba

l tem

pera

ture

s ke

ep ri

sing

?

�O

ne im

porta

nt is

sue

is w

ater

sca

rcity

, if t

empe

ratu

res

rise

and

drou

ghts

bec

ome

mor

e co

mm

on

�Th

e ca

se o

f Cha

d: L

ake

Cha

d, o

nce

the

wor

ld�s

6th

larg

est l

ake,

but

it is

dry

ing

up. I

t is

curr

ently

onl

y 10

-20

% o

f its

form

er s

ize.

For

mer

fish

ing

tow

ns a

re d

eser

t

�D

eser

tific

atio

n, p

lus

dam

min

g of

rive

rs fo

r hyd

ro-

elec

tric

pow

er, a

re b

oth

to b

lam

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Whi

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Whi

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Whi

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Map

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