## Function T-Test-Matched

(

**t-test-matched** &rest < args > )

t-test-matched (sample1 sample2 &optional (tails both))

Returns the t-statistic for two matched samples, which should be equal-length

sequences of numbers. Let D=mean1-mean2. The null hypothesis is that D=0. The

alternative hypothesis is specified by ` tails': `

:both' means D/=0, ` :positive'<br> means D>0, and `

:negative' means D<0. Unless you're using :both tails, be

careful what order the two samples are in: it matters!

The function also returns the significance, the standard error, and the degrees

of freedom. Signals ` standard-error-is-zero' if that condition occurs. Signals<br>`

insufficient-data' unless there are at least two elements in each sample.