4. Determining power is important when planning a study. There is general agreement among researchers that a study should have 80% power to be worth doing. There are a number of ways to increase the power of a planned study, including increasing the predicted difference between the population means; decreasing the population standard deviation; using a larger sample size; using a more lenient significance level; using a onetailed test; and using a more sensitive hypothesis-testing procedure (if one is available).