1M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Lesson Objectives - M02

Understand “Scales of Measurement.”

Understand “Quantitative Variables”and the two types.

Understand “Categorical Variables”and the three types.

Determine which of the above to useto make a decision.

2M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

STATISTICS is the science of

collecting,collecting, organizing, organizing, summarizing, summarizing, andand interpreting… interpreting…

DATA

for the purpose of _______________.

3M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Problem Situation

Your first job as a newly named marketing associate for Taco Casa:

Manage a task force to determine the location of a new store from among four candidate cities.

What do you do?

4M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Must make a decision!

Where do you start?

5M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Back to Taco Casa Problem:

Your task force is charged with comparing characteristics of households in the four different cities (market profiles).

6M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Variables that may be usefulfor site selection.

7M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Variables that may be usefulfor site selection.

8M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Variables that may be usefulfor site selection.

9M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

What to measure?

How to measure?

Best data gathering approach?

Designing a data collection is not simple!

10M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Drawing conclusions about

the population (___________),

based on a sample

(___________).

Statistical Inference

11M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Definition: Variable

Any measurable characteristic of a person or thing.

In a data set, always observe the:

i) number of variables

ii) types of variables.

In a data set, always observe the:

i) number of variables

ii) types of variables.

12M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Rule of Thumb:

If averages or differences have meaning, a variable is ________________.

Ex:

13M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Types of Quantitative Variables

Discrete: _____________ values with gaps between them. Note: Not necessarily integers. May be an infinite number of values.

Continuous: ___________ in an interval can occur.

14M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Scales of Measurement

Nominal

Ordinal

Interval

Ratio

Each value is a __________

________ has meaning

Units of measurement

True absolute zero

15M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Rule of Thumb:

A variable that classifies people or things, is _________ or ______________.

Ex: sex, political affiliation, race, country of origin.

16M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Types of Qualitative Variables

Nominal: Numbers are used to “NAME” categories.____________: The categories have a natural ordering.Binary: Two categories (usually assigned values of “0” or “1”).

17M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Identify the type:

Height:

Stock Quote:

Age:

Course Grade:

Football jersey number:

18M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Identify the type:

Answer to aT/F Question:

Number ofcorrect T/Fanswers in 5 questions:

Proportion ofcorrect T/Fanswers in 5 questions:

19M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Handout: Data for 100 Households (FAM100.DAT)

Income1 Annual income of principal wage earner

Income2 Annual income of secondary wage earner

FamSize Family size

Own? Own or rent (1 = own, 0 = rent)

TotalDebt Total indebtedness (excluding mortgage)

Housing Monthly house payment or rent

Utility Average monthly utility expenditure

City City of residence (1, 2, 3, 4)

20M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

After we collect data, then what?

Organize / Summarize Data

Graphical Numerical

21M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

22M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Descriptive Statistics:

numerical summaries and/or graphical display of (sample) data.

Inferential Statistics:

Using sample data to make conclusions about the population from which the sample was taken.

23M02-Data Collection/TypesM02-Data Collection/Types Department of ISM, University of Alabama, 1995-2003

Population:

collection of all items of interest in a study

Sample: subset selected to be representative of the population