- The second step is to choose a
significance level. Assume the .05 level
is chosen.

- The third step is to compute the difference
between sample means (M
_{d}). In this example, M_{t}= 63.89, M_{N}= 46.79 and M_{d}= MT_{}- M_{N}= 17.10.

- The fourth step is to compute p, the
probability (or probability value) of
obtaining a difference between and the value specified by the null
hypothesis (0) as large or larger than the difference obtained in the
experiment. Applying the general formula,

where M_{d }is the difference between sample means, µ_{1}- µ_{2}is the difference between population means specified by the null hypothesis (usually zero), and is the estimated standard error of the difference between means.