I'd like to know the required sample size needed to sample a population within 14.7 units of its mean, where the sd = 46, alpha = 0.01, and power = 0.99. I try R's
> power.t.test(delta=14.7, sd=46, sig.level=0.01, power=0.99, type="one.sample") One-sample t test power calculation n = 238.6533 delta = 14.7 sd = 46 sig.level = 0.01 power = 0.99 alternative = two.sided
Numerically, however, this doesn't seem right: I can run 1000 draws of n samples and it turns out n should be ~75 to be 99% certain of being within 10% of the population mean. Why? Thanks.