PRELIMINARY DEFINITIONS

frequency → count or number

relative frequency → proportion/percentage, calculated as count/total

population → entire group of subjects

sample → subgroup of subjects within population

• we obtain data from sample, not population

parameter → numerical measurement describing characteristics of population

statistic → numerical measurement describing characteristics of sample

sampling variation → phenomenon where we see different values occurring in different random samples of the same size drawn from the same population

• vary from sample to sample

VARIABLES

• characteristic or feature recorded about each individual

2 MAIN TYPES:

Categorical

• non-numerical observations

• never used directly in calculations

ex. gender, political party, major/department

Quantitative

• numerical observations

• used directly in calculations

• always have units of measure

ex. age, height, income, score