The entire group of individuals is called the population ex. a researcher may be studying the relationship between class size and academic performance for the population of 3rd grade kids. Usually populations are so large that a sample is used to represent the population. The goal is to use the results obtained from the sample to help answer questions about the population ex. may sample 50 men and 50 women to test for sex differences in verbal memory performance. Population characteristics are called parameters, sample characteristics are called statistics. Really interested in what happens in the population but usually can just test a sample of the population *s +s = sample and statistics (related!) A variable is a characteristic or condition that can change or take on different. Most research begins with a general question about the relationship between two variables for a specific group of individuals there"s usually more than one variable.