ABSTRACT
Fundamental to the strategy of science is the formulation and testing of hypotheses about populations or the effects of experimental conditions on criterion variables. Hypotheses derived from the researcher's theory about some social phenomenon are called research or alternative hypotheses. Null hypotheses are, in a sense, the reverse of research hypotheses. In specifying a research hypothesis, we can specify either a nondirectional or a directional hypothesis. Testing hypotheses means subjecting them to some sort of empirical scrutiny to determine whether they are supported or refuted by what the researcher observes. In order to introduce some objectivity in the decision-making process, conventional decision rules have been set up to assist researchers in deciding when to reject the null hypothesis. Testing nondirectional and directional hypotheses is associated with the use of the two-tailed and one-tailed test of significance. A two-tailed test will test both sides of the probability curve.
