Explain why causes that are both necessary and sufficient are difficult to identify in the social sciences.
4Reliability vs. Validity
Differentiate reliability from validity. Which is more important? Why?
5.Probability Sampling
Suppose you were asked by the principal of a local high school to do a survey of the student body. The principal believes it is sufficient to stop students on their way to the library and hand out the questionnaire. You argue for a probability sample instead. State your argument, and give at least two reasons why probability sampling might
be preferred.
6Question
Differentiate internal from external invalidity. Describe at least two factors contributing to each. Which one of the two--internal or external invalidity--is more serious? Why?