Analyzing Observational Data

Functions of Statistics

Descriptive: Organize and summarize data to make them more intelligible.

Inferential: Make inferences to generalize from data (e.g. from sample data to entire population).

Univariate Analysis

Do you have sufficient variation?

How should you collapse your categories?

Creating Frequency Distributions

List all attributes of outcome – should be exhaustive/mutually exclusive.

Add up number of cases in each category.

Frequency distribution of snacks eaten at RU snack bar.

Percentage distribution of number of bites/licks taken to finish ice cream cone

Descriptive Statistics

Measures of central tendency

Mean: add all responses and divide by total number of respondents

Measures of dispersion

Range: endpoints

Shape of distribution

E.g. Histogram

Frequency distribution of snacks chosen at RU snack bar, by gender

Percentage distribution of snacks chosen at RU snack bar, by gender

Percentage distribution of number of licks/bites to finish ice cream, by gender.

Summary statistics of bites/licks taken to eat ice cream, by gender.