1 - 1 Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. What is Statistics?

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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.

What is Statistics?What is Statistics?

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When you have completed this chapter, you will be able to:

Explain what is meant by statistics.

Identify the role of statistics in the development of knowledge and everyday life.

Explain what is meant by descriptive statistics and inferential statistics.

1.

2.

3.

4.

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Distinguish between a qualitative variable and a quantitative variable.

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5.

6.

7.

8.

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Distinguish among the nominal, ordinal, interval,

and ratio levels of measurement.

Collect data from published and unpublished sources.

Identify abuses of statistics.

Distinguish between a discrete variable and a continuous variable.

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9. Gain an overview of the art and science of

statistics.

We recommend that you read this chapter at least twice, once at the beginning and once at the end of your course!

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…it is the art and science of…

collecting

organizing

presenting data

drawing inferences from a

sample of information

about an entire population

as well as

predicting and developing policy analysis

What is

Meant by

Statistics?

What is

Meant by

Statistics?

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in everyday life

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Who uses Statistics?Who uses Statistics?

Those using Statistical techniques include :

MarketersMarketers

AccountantsAccountants

HospitalsHospitals

InvestorsInvestors

EconomistsEconomistsSports peopleSports people

StatisticiansStatisticians ConsumersConsumers

EducatorsEducatorsQuality ControllersQuality Controllers

PoliticiansPoliticians PhysiciansPhysicians

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Weather Forecasters


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Sports

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Types of Statistics

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Types of Statistics

Methods of… collecting

organizing presenting

and

analyzing data

Methods of… collecting

organizing presenting

and

analyzing data

Science of… making inferences about a population,

based on sample information.

Science of… making inferences about a population,

based on sample information.

DescriptiveDescriptive InferentialInferential

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Identify the following…

C. Wine tasters sip a few drops of wine to make a decision

with respect to all the wine waiting to be released for sale.

A. A Gallup poll found that 83% of the people in a survey knew

which country won the gold medal in Men’s Hockey in 2002.

B. The accounting department of a firm will select a sample of invoices to check for accuracy

of all the invoices of the company.

DescriptiveDescriptive InferentialInferential

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We start off with particular observations from the real world and draw conclusions about the general patterns in the real world!

We start off with particular observations from the real world and draw conclusions about the general patterns in the real world!1. Define the experimental goal or a working hypothesis

2. Design an experiment3. Collect data4. Estimate the values/relations5. Draw inferences6. Predict and prepare policy analysis

Chapters 8 and 12

Chapters 3 and 4

Chapters 5,7,8 and 9

The Method of Experimentation


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Definitions & Assumptions

Definitions & Assumptions

Rules of Logic

Rules of Logic

Implications or Hypotheses

Implications or Hypotheses

Objective or Working-

Hypothesis

Objective or Working-

Hypothesis

Experimental Design & Data Collection

Experimental Design & Data Collection

Statistical Techniques

Statistical Techniques

Inductive MethodInductive Method Deductive MethodDeductive Method



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A study was undertaken to estimate the average height of penguins in Antarctica.

Let’s review the steps they would take to prepare the estimate.

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A population is a collection of all possible

individuals, objects, or

measurements of interest

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Take a

What we now need is…What we now need is…

From

…which are deemed to be representative of the…which are deemed to be representative of the

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Take a Measurement for each one

in the sample

Take a Measurement for each one

in the sample Record

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…to put the data into a

readable and understandable

format!

Displaying Data ResultsDisplaying Data Results

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Two methods that can be used to ‘see’

what the data conveys are

Tables and Graphs/Charts

More on these in chapter 2…

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Tables … are an efficient method of displaying data

and depicting data accurately.

e.g.


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Line ScatterScatter

HistogramHistogram

PiePie

BarBar


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Why take a sample instead of studying every member of the population?Why take a sample instead of studying every member of the population?

Costs of surveying the entire population may be too large or prohibitive

Destruction of elements during investigation

Accuracy of results

More in chapter 8 …

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Data are everywhere

Statistical techniques are used to make many decision that affect our lives

No matter what your future line of work, you will make decisions that involve data. An understanding of statistical methods will help you make these decisions more effectively.

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Types of Data

a characteristic of

a population or sample

a characteristic of

a population or sample

that is of interest to usthat is of interest to us

A Variable

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QuantitativeQualitative

NumericalObservations

Categorical Observations

Types of Data

Variables

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Country of BirthU.K.

GermanyTaiwanChinaIndiaJapanRussia

Country of BirthU.K.

GermanyTaiwanChinaIndiaJapanRussia

Eye ColourBlue

BrownHazelGreenRed

Eye ColourBlue

BrownHazelGreenRed

GenderMale

Female

GenderMale

Female

Qualitative – or AttributeQualitative – or Attribute

Variables

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Minutes to end of Class

55453050

Minutes to end of Class

55453050

Number of Children in

a Family

1234 …

Number of Children in

a Family

1234 …

Number of Two-Door

Garages in a

Street

10203040...

Number of Two-Door

Garages in a

Street

10203040...

Number of Satisfied Maple Leafs Fans

0203040…

Number of Satisfied Maple Leafs Fans

0203040…

Quantitative – NumericQuantitative – Numeric

Variables

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Quantitative


… can be classified as either Discrete orContinuous

DiscreteDiscrete … can only assume certain values and there are usually “gaps”

between values

… can only assume certain values and there are usually “gaps”

between valuese.g. - Number of bedrooms in a house - Number of hammers sold (1,2,3,…etc)

Variables

CharacteristicsCharacteristics

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ContinuousContinuous … can assume any value

within a specified range!

… can assume any value

within a specified range!e.g. - Pressure in a tire

- Weight of a pork chop - Height of students in a class

Quantitative


… can be classified as either Discrete orContinuous

CharacteristicsCharacteristics

Variables

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Summary of Types of VariablesSummary of Types of Variables

DataData

Qualitative Categorical

Observations

QuantitativeNumerical

Observations

DiscreteDiscrete ContinuousContinuous

(number of children) (time used for an exam)

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Statistical Abstracts

Published Data

Sources of Statistical Information

WeatherSports

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InternetInternet


www.strategis.gc.ca

www.bankofcanada.ca

Government of Canada & ProvincesGovernment of Canada & Provinces www.gc.ca

www.theweathernetwork.com

www.mcgrawhill.ca/college/lind

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International


www.census.gov

www.un.org

www.bls.gov/

www.oecd.org

IMF www.imf.org

www.worldbank.org/

Organization for Economic Co-operation

and Development

Organization for Economic Co-operation

and Development

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How to collect data…

Commissioned surveys:Commissioned surveys:


To develop information for the survey that they are doing, pollsters often contact the selected ‘sample population’.

For Example…At home, over the telephone, by mail, by email, in the street, and at shopping malls!

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Nominal

Ordinal

Interval

Ratio

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Nominal

Data can only be classified into categories or counted and cannot be arranged in any particular order

Data can only be classified into categories or counted and cannot be arranged in any particular order

ExampleExample M & Ms

Classification:Classification:

Category:Category: Candy

By Colour only(No natural order)

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Nominal

ExampleExample M & Ms

Exhaustive:Exhaustive:

Mutually Exclusive:Mutually Exclusive:

…where an individual, object, or measurement is included in ONLY ONE CATEGORY

…where each individual, object, or measurement MUST APPEAR in one of the categories

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Ordinal

…involves data arranged in some order,but the differences between data values

cannot be determined or are meaningless!

ExampleExample During a taste test of 4 soft drinks:

Mello Yello was ranked number……..…. 1.

Sprite number……………………………. 2.

Seven Up number..…………………..…... 3.

Orange Crush number ….……………….4.

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Interval

…similar to the Ordinal Level, with the additional property that meaningful amounts of differences between

data values can be determined.

There is no natural zero point

ExampleExample

Temperature on the Celsius scale.

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Ratio

…the Interval Level with an inherent zero starting point.

Differences and ratios are meaningful for this level of measurement.

ExamplesExamplesMonthly income of surgeons

Distance travelled by manufacturer’s representatives per month

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Benjamin Disraeli said…

“There are three kinds of lies…

Benjamin Disraeli said…

“There are three kinds of lies…

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Figures don’t lie.

Liars figure!

Figures don’t lie.

Liars figure!

Caution

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As you begin to study statistical methods, you are cautioned to take what you see

published as “statistical facts” with a healthy grain of

skepticism!

As you begin to study statistical methods, you are cautioned to take what you see

published as “statistical facts” with a healthy grain of

skepticism!

… an average may not be representative of all the data… an average may not be representative of all the data

… graphs can also be misleading… graphs can also be misleading

… be sure to study the sampling methods… be sure to study the sampling methods

For Example

Caution

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Caution

Review the following three slides and notice the effect that the

different scales have on your interpretation of the pattern between Crime and Unemployment Rates.

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1986 - 1999

0 1 2 3 4 5 6 7 8 9 10 11 12

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Cri

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Unemployment Rate (%)

Chart 1-11AChart 1-11A

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1986 -1999

7 8 9 10 11 12

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Chart 1-11BChart 1-11B

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1986 -1999Chart 1-11CChart 1-11C

3200

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Unemployment Rate (%)7 8 9 10 11 12

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Test your learning…Test your learning…

www.mcgrawhill.ca/college/lindClick on…Click on…

Online Learning Centrefor quizzes

extra contentdata setssearchable glossaryaccess to Statistics Canada’s E-Stat data…and much more!

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This completes Chapter 1.This completes Chapter 1.

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