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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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.
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.
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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Collect data from published and unpublished sources.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
Who uses Statistics?Who uses Statistics?
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Who uses Statistics?Who uses Statistics?
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
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
The Method of Experimentation
The Method of Experimentation
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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.
More on these in chapter 2…
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Line ScatterScatter
HistogramHistogram
PiePie
BarBar
More on these in chapter 2…
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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
NumericalObservations
… 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
NumericalObservations
… 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
Sources of Statistical Information
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
Sources of Statistical Information
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:
Sources of Statistical Information
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
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1986 -1999Chart 1-11CChart 1-11C
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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.