(solution) One major reason that the two-sample t procedures are widely used is that they are quite robust….

(solution) One major reason that the two-sample t procedures are widely used is that they are quite robust….

One major reason that the two-sample t procedures are widely used is that they are quite robust. This means that (a) t procedures do not require that we know the standard deviations of the populations. (b) confidence levels and P-values from the t procedures are quite accurate even if the population distribution is not exactly Normal. (c) t procedures compare population means, a comparison that answers many practical questions.