. . parametric techniques are [considered] the tests of choice if their assumptions are met.
Some of the assumptions for parametric tests include:
(1) the observations must be independent (that is, the selection of any one case should not
affect the chances for any other case to be selected in the sample);
(2) the observation should be drawn from normally distributed populations;
(3) these populations should have equal variance;
(4) the measurement scales should be at least interval so that arithmetic operations can be
used with them.