Statistics Dont Delete

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Chapter

One

What is Statistics??


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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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Types of Statistics

EXAMPLE 2: According

to Consumer Reports,

General Electric washing

machine owners reported9 problems per 100

machines during 2001.

The statistic 9 describes

the number of problemsout of every 100 machines.

Descriptive Statistics: Methods of organizing,summarizing, and presenting data in an informative way.

EXAMPLE 1: A

Gallup poll found that

49% of the people in a

survey knew the nameof the first book of the

Bible. The statistic 49

describes the number

out of every 100persons who knew the

answer.


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DESCRIPTIVE STATISTICS

Most of the Statistical Information in

newspapers, magazines, company reports,

and other publications consists of data that

are summarized and presented in a form thatis easy for the reader to understand. Such

summaries of data, which may be tabular,

graphical or numerical, are referred to asDescriptive Statistics


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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: themethods used todetermine something about a population on the basis

ofa sample.


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Population (N) Sample (n)

Samples and Populations


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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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Using Statistics (Two Categories)

Inferential Statistics Predict and forecast

values of population

parameters Test hypotheses about

values of population

parameters

Make decisions

Descriptive Statistics Collect

Organize

Summarize

Display

Analyze


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Types of Variables

Gender EyeColor

For a Qualitative or Attribute Variable thecharacteristic being studied is nonnumeric.

Type of carState of

Birth


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Types of Variables

Number of children in a family

In a Quantitative Variable information 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

Discrete or Continuous.


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Types of Variables

The height of students in a class.

A Continuous Variable can 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

countable measurable

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Contd

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HOW DO YOU DISTINGUISH BETWEEN

CONTINUOUS AND DISCRETE

CONTINUOUS DISCRETE

They are real numbers

Normally, they aremeasured values

They can not take a

single value. There is an

area associated with itThey are continuous

Requires less sample

size

They are whole numbers

Normally, they are countedvalues

They can take only Zero or

non-fractional positive

valuesThey are in steps of 1

Requires more sample size to

have the more precision

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SOURCES OF DATA

PRIMARY SOURCE

SECONDARY SOURCE

INERNAL RECORDS

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DATA SOURCES

Data are also available from a variety of industry

associations and special interest organizations

E.g.: Internet used by Companies

Maintaining websites that provide information like:General Information about the company

Data on Sales

Number of Employees

Number of ProductsProduct Prices

Product Specifications

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More Benefits of Using Internet

Access to Stock Quotes

Meal Prices at Restaurants

Salary Data

And Other Infinite Variety of information

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Managers wanting to use data and Statistical

Analyses as an aid to decision making must be aware

of the time and cost required to obtain the data

Use of existing data sources is desirable when data

must be obtained in a relatively short period of time

If important data are not readily available from an

existing source, the additional time and cost involved

in obtaining the data must be taken into account.

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In all cases, the decision maker should consider the

contribution of the statistical analysis to the decision-

making process

The cost of data acquisition and subsequent

statistical analysis should not exceed the savings

generated by using the information to make a better

decision.

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Levels of Measurement

There are four levels ofdata

Nominal

OrdinalInterval

Ratio

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Qualitative -

Categorical or

Nominal:

Examples are-

Color

Gender

Nationality

Quantitative -

Measurable or

Countable:

Examples are-

Temperatures

Salaries

Number of pointsscored on a 100

point exam

Types of Data

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Nominal data

Nominal levelData that is

classified into

categories and

cannot be arranged

in any particularorder.

Gender

EyeColor

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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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During a taste test

of 4 soft drinks,

Coca Cola wasranked 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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Temperature on theFahrenheit scale.

Interval levelSimilar to the ordinal level, with the additionalproperty that meaningful amounts of differencesbetween data values can be determined. There is nonatural zero point.

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Monthly incomeof surgeons

Miles traveled by salesrepresentative in a month

Ratio level: the interval level with an inherentzero starting point. Differences and ratios are

meaningful for this level of measurement.

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Nominal Scale- groups or classes

Gender

Ordinal Scale- order matters

Ranks (top ten videos)

Interval Scale- difference or distance matters

has arbitrary zero value.

Temperatures (0F, 0C)

Ratio Scale- Ratio mattershas a natural zero

value.

Salaries

Scales of Measurement

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Answer these

What is the level of measurement for each of the

following variables?

Student IQ Ratings

Distance students travel to class

Student scores on the first statistics test

A Classification of the students by State of Birth

A ranking of students by freshman, sophomore, juniorand senior

Number of hours students study per week

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What is the level of measurement for these items

related to the newspaper business?

The number of papers sold each Sunday during the

year 2004

The departments, such as Editorial, Advertising,

Sports etc

A Summary of the number of papers sold by country

The number of years with the paper for each employee

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Cross-Sectional and Time Series Data

Cross-Sectional data are the data collected at

the same or approximately the same point in

time.

Time series data are data collected over

several time periods.

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QUESTION

ANDANSWERS

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TESTYOURSELF

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The science of statistics includes which of the

following:

A. Organizing data.

B. Presenting data.C. Interpreting data.

D. All of the above.Option

D

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In descriptive statistics our main objective is to

A. Describe the population.

B. Describe the data we collected.

C. Infer something about the population.

D. Compute an average.

Option B

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Which of the following statements is true regarding apopulation?

A. It must be a large number of values.

B. It must refer to people.

C. It is a collection individuals, objects, ormeasurements.

D. None of the above.

Option C

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Which of the following statements is true regarding a

sample?

A. It is a part of population.

B. It must contain at least five observations.

C. It refers to descriptive statistics.

D. All of the above are correct

Option A

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A discrete variable is

A. An example of a qualitative variable.

B. Can assume only whole number values.

C. Can assume only certain clearly separated values.D. Cannot be negative.

Option C

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A Nominal Scale Variable is

A. Usually the result of counting something.

B. Has a meaningful zero point.

C. May assume negative values.

D. Cannot have more than two categories.Option

D

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The ratio scale of measurement

A. Usually involves ranking.

B. Cannot assume negative values.

C. Has a meaningful zero point.D. Is usually based on counting.

Option C

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The ordinal scale of measurement

A. Has a meaningful zero point.

B. Is based on ranks

C. Cannot assume negative values.

D. All of the above

Option B

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Categories are exhaustive when

A. There is a meaningful zero point.

B. The objects can be ranked.

C. Each object must appear in at least one category.D. Each object can be included in only one category.

Option C

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