Alternative Hypothesis

This is the hypothesis that is accepted when the null hypothesis is rejected. The alternative hypothesis can be expressed as either a non-directional hypothesis or a directional hypothesis. If the researcher employs a directional hypothesis, the rejection of the null hypothesis requires not only a significant finding, but that the data is consistent with the directional hypothesis. For example, if the alternative hypothesis predicts that the mean effect of a drug alleviates symptoms more than a placebo, not only does the analysis need to be significant, but the mean symptom alleviation of the drug needs to be greater than that of the placebo to reject the null hypothesis and accept the alternative hypothesis. The alternative hypothesis is sometimes written as H1: