Simple empirical formulae are presented for estimating appropriate sample size for simple randomized analysis of variance designs involving 2, 3, 4 or 5 treatments. In order to use these formulae one must specify the magnitude of a meaningful treatment difference and must have an estimate of the error variance. Sample size estimates derived from the simple formulae have been found to differ from values obtained using constant power curves by no more than one sampling unit on the low side and no more than two sampling units on the high side.
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