Table MTE0U. Two group t-test of equivalence in means (unequal n’s)

This sample size table is for a one-sided two-group t-test of the null hypothesis that the means are not equivalent (i.e. that the test drug mean is “worse than” the standard drug mean by an amount Δ0 or more). The alternative hypothesis is that the means are equivalent, defined as differing by only Δ1 (usually 0). Computed using t and non-central t distributions; the non- centrality parameter is (δ)(sqrt(n1))(sqrt(r))/sqrt(1+r) where δ is defined in the table row title. See nQuery Advisor® manual Appendix for details of computing method for t. Results for this table then will agree exactly with those for Table MTT0U, the two-sample t-test for unequal n’s, when a one-sided test is selected in MTT0U and the numeric values for effect size are the same. Figure MTE0U shows computations for two examples. Additional values tested: parameter values same as for MTT0 with sample size ratios of 1, 2, 4 and 1/4. Checked against MTT0U and two-group t-test in DOS software Stat-Power version 2.0 by Bavry JL (1991) Scientific Software, Inc and Statistical System Power Analysis by Hintze JL (1991) BMDP Statistical Software.

Figure MTE0U. nQuery Advisor® 7.0 solved for sample size in each column.