I want to understand the difference between Completely Randomized Design and Randomized Complete Block Design. Say for this example how we can categorize? An experiment is conducted to compare the starting salaries of male and female college graduates who find jobs. Pairs are formed by choosing a male and a female, with the same major and similar grade point averages. Suppose a random sample of ten pairs is formed by this method and the starting salary of each person is ascertained with the resulting data (not shown). I just want to know the basic concept with this design structure. Thanks.