Chapter 01 What is Statistics?
Transcript of Chapter 01 What is Statistics?
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Chapter
One
McGraw-Hill/Irwin 2005 The McGraw-Hill Companies, Inc., All Rights Reserved.
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Chapter One
What is Statistics?
GOALS
When you have completed this chapter, you will be able to:
ONE
Understand why we study statistics.
TWO
Explain what is meant by descriptive statistics and inferential statistics.THREE
Distinguish between a qualitative variable and a quantitative variable.
FOUR
Distinguish between a discrete variable and a continuous variable.FIVE
Distinguish among the nominal, ordinal, interval, and ratio levels
of measurement.
SIX
Define the terms mutually exclusive and exhaustive.Goals
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What is Meant by Statistics?
Statistics is the science
of collecting, organizing,presenting, analyzing,
and interpreting
numerical data to assist
in making more
effective decisions.
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Who Uses Statistics?
Statistical techniques are
used extensively bymarketing, accounting,
quality control,
consumers, professional
sports people, hospital
administrators,
educators, politicians,
physicians, and manyothers.
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Types of Statistics
EXAMPLE : According to Consumer Reports,
General Electric washing machine owners reported
9 problems per 100 machines during 2001. The
statistic 9 describes the number of problems out ofevery 100 machines.
Descriptive Statistics: Methods of organizing,summarizing, and presenting data in an informative way.
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Types of Statistics
APopulationis a
Collection
of all possibleindividuals,objects, ormeasurements of
interest.
ASampleis a
portion, or part,of the population
of interest
Inferential Statistics:A decision, estimate,prediction, or generalization about a population,
based on a sample.
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Types of Statistics
(examples of inferential statistics)
Example 2: Wine
tasters sip a few drops
of wine to make adecision with respect
to all the wine waiting
to be released for sale.
Example 1: TV
networks constantly
monitor thepopularity of their
programs by hiring
Nielsen and other
organizations tosample the
preferences of TV
viewers.
Example 3: The accounting
department of a large firm will
select a sample of the invoices to
check for accuracy for all theinvoices of the company.
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Types of Variables
Gender
Eye
Color
For a Qualitative or Attribute Variablethecharacteristic being studied is nonnumeric.
Type of car
State of
irth
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Types of Variables
Number of children in a family
In a Quantitative Variableinformation is
reported numerically.
Balance in your checking account
Minutes remaining in class
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Types of Variables
Discrete Variables:can only assumecertain values and there are usually gaps
between values.
Example: the number of
bedrooms in a house, or
the number of hammers
sold at the local Home
Depot (1,2,3,,etc).
Quantitative variables can be classified as either
Discreteor Continuous.
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Types of Variables
The height of students in a class.
A Continuous Variablecan assume anyvalue within a specified range.
The pressure in a tire
The weight of a pork chop
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Summary of Types of Variables
Qualitative or attribute
(type of car owned)
discrete
(number of children)
continuous
(time taken for an exam)
Quantitative or numerical
DATA
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Levels of Measurement
There are four levels ofdata
Nominal
OrdinalInterval
Ratio
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Nominal data
Nominal levelData that is
classified into
categories and
cannot be arranged
in any particularorder.
Gender
Eye
Color
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Levels of Measurement
Mutually exclusiveAn individual, object, or
measurement is included in only
one category.
Nominal level variables must be:
Exhaustive
Each individual, object, ormeasurement must appear in one
of the categories.
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Levels of Measurement
During a taste test
of 4 soft drinks,
Coca Cola was
ranked number 1,
Dr. Pepper number
2, Pepsi number 3,
and Root Beer
number 4.
Ordinal level: involves data arranged in someorder, but the differences between data values cannot
be determined or are meaningless.
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3
4
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Levels of Measurement
Temperature on the
Fahrenheit scale
Interval levelSimilar to the ordinal level, with the additional
property that meaningful amounts of differencesbetween data values can be determined. There is nonatural zero point.
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Levels of Measurement
Monthly income
of surgeons
Miles traveled by sales
representative in a month
Ratio level:the interval level with an inherentzero starting point. Differences and ratios are
meaningful for this level of measurement.