With 35 patients allocated to each group, assuming the Student's T-test will be used to determine the differences between two independent samples, effect sizes d>0.6 will be found statistically significant with alpha .05 and power .80. In practical terms, since the PSS validation samples showed a mean about 13.5 with variance=6.2, only averaged differences greater than 1.5 raw score points in PSS will be found statistically significant.