The following output (from \(\mathrm{R}\) ) presents the results of a power calculation for a test of the difference between two means \(\mu_{1}-\mu_{2}\).

a. Is the power calculated for a one-tailed or a two-tailed test?

b. If the sample sizes were 50 in each group, would the power be less than 0.9 , greater than 0.9 , or is it impossible to tell from the output? Explain.

c. If the difference (delta) were 4 , would the power be less than 0.9 , greater than 0.9 , or is it impossible to tell from the output? Explain.

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Two-sample t test power calculation. n = 59.35157 delta = 3 sd = 5 sig. level 0.05 power 0.9 = = alternative NOTE: n is number in *each* group two.sided