Estimating Power (3 of 4)

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How much power is enough power? Naturally, the more power the better. However, in some experiments it is very time consuming and expensive to run each subject. In these experiments, the experimenter usually must accept less power than is typically found in experiments in which subjects can be run cheaply and easily. In any case, power below .25 would almost always be considered too low and power above .80 would be considered satisfactory. Keep in mind that a Type II error is not necessarily so bad since a failure to reject the null hypothesis does not mean that the research hypothesis should be abandoned. If the results are suggestive, further experiments should be conducted to see if the existence of the effect can be confirmed. The power of the two experiments taken together will be greater than the power of either one.