1. mean An average, computed by summing the
values of several observations and dividing by the number of observations.
If you now have a GPA of 4 based on 10 courses, and you get an F in this
course, your new GPA (mean) would be 3.6.
2. median Another average, representing the value of the "middle" case in a rank-ordered set of observations. If the ages of five men are 16, 17, 20, 54, and 88, the median would be 20 and the mean would be 39.
3. mode An average representing the most frequently observed value or attribute. If a sample contains 1,000 Jews, 275 Christians, and 33 Muslims, Jews are the modal category.
4. dependent variable That variable that is assumed to depend on or by caused by another (called the independent variable). If you find that income is partly a function of amount of formal education, income is being treated as a dependent variable.
5. independent variable A variable whose values are not problematical in an analysis but are taken as simply given. An independent variable is presumed to cause or determine a dependent variable. If we find that mortality is partially a function of dietary regimen dietary regimen is the independent variable and mortality is the dependent variable.
6. ecological fallacy Erroneously drawing conclusions about individuals based solely on the observation of groups.
7. units of analysis The what or whom being studied. It is critical to identify ones units of analysis in order to formulate a testable hypothesis.
8. hypothesis An expectation about the nature of things derived from a theory. It is a statement of something that ought to be observed in the real world if the theory is correct.
9. simple random sample A type of probability sample in which the units composing a population are assigned numbers, a set of random numbers is then generated, and the units having those numbers are included in the sample.
10. representativeness That quality of a sample of having the same distribution of characteristics as the population from which it was selected. By implication, descriptions and explanations derived from an analysis of the sample may be assumed to represent similar ones in the population. Representativeness is enhanced by probability sampling and provides for generalizability and the use of inferential statistics.