Statistics – Appendix Revision 3
1. Introduction – Terms
A. Population – Contains all instances to which you intend to generalize

All the things you are going to talk about, usually very large
B. Sample – A subset of a population

Any part of a population

Population sample versus representative sample

Representative sample must be selected carefully to make accurate
predictions, represents the population.
Know what are:

Crosssection of a population:
20% Hispanics (pop.)
20% (rep. sample)
50% Females (pop.)
50% (rep. sample)

Each member of the population must have equal chance of being selected

Every selection must be independent of the other selection – every 10
th
person
is a biased sample.
C. Parameter – A quantitative characteristic of a promotion

Samples the population to generalize
D. Statistic – A quantitative characteristic of a sample
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Statistics is the parameter, what you collect
2. Descriptive Statistics
A. Purpose – To summarize and to describe
B. Types
1. Graphs and tables
2. Measure of central tendency
A. Meanarithmetic average
Example: 9 workers packed 309 cases of bread. What is the average
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 Spring '07
 Pennebaker
 Mean, 50%, representative, 12 months, 20%

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