ABSTRACT
Relationships that teachers find among variables help them to explain, understand, control, predict, and so forth. There are two kinds of analytic activity between which the investigator shuttles back and forth when he seeks to determine causal and noncausal relationships. One is getting ideas about relationships, which he then formulates as hypotheses. The other is examining and testing the hypotheses. Many of the most important scientific ideas have come to scientists as they casually observed the world about them. The distinction between theory and hypotheses derived from casual experience is important and hard to grasp. Some apparent relationships are massively supported; for example, insurance data on tens of millions of people show conclusively that women live to be older than men. Finding the meaningful relationships within a complex set of variables requires close study of them.
