t-test-one-sample (data tails &optional (h0-mean 0) &key start end key)
Returns the t-statistic for the mean of the data, which should be a sequence
of numbers. Let D be the sample mean. The null hypothesis is that D equals the
H0-mean.' The alternative hypothesis is specified by tails':
:both' means D<br> /= H0-mean, :positive' means D > H0-mean, and
:negative' means D < H0-mean.<br> <br> The function also returns the significance, the standard error, and the degrees<br> of freedom. Signals zero-variance' if that condition occurs. Signals
`insufficient-data' unless there are at least two elements in the sample.