T test of mean
From OPOSSEM
<math>t = \frac {\bar{y}-\mu_0}{\frac {s_\bar{y}}{\sqrt{n-1}}}</math>, where <math>\mu_0 </math> is the test value and the <math>df = n-1</math>.
<math>t = \frac {\bar{y}-\mu_0}{\frac {s_\bar{y}}{\sqrt{n-1}}}</math>, where <math>\mu_0 </math> is the test value and the <math>df = n-1</math>.