Functional anatomy of the null hypothesis and of tests of it.

The author compared simulations of the "true" null hypothesis (zeta) test, in which sigma was known and fixed, with the t test, in which s, an estimate of sigma, was calculated from the sample because the t test was used to emulate the "true" test. The true null hypothesis test bears exclusively on calculating the probability that a sample distance (mean) is larger than a specified value. The results showed that the value of t was sensitive to sampling fluctuations in both distance and standard error. Large values of t reflect small standard errors when n is small. The value of t achieves sensitivity primarily to distance only when the sample sizes are large. One cannot make a definitive statement about the probability or "significance" of a distance solely on the basis of the value of t.