The chi square for table 3.2 was equal to 12.52. V would be equal to 12.52 divided by the square root of the product of 900 and 1 or 12.52 divided by 30 or 0.42. Cramer's V should be used when one or both of the variables consist of an unordered set of categories. It varies from 0 to 1. The closer it is to 0, the weaker the relationship and the closer to 1, the stronger the relationship.
V can never be negative.
Gamma assumes that both of the variables consist of ordered categories. To understand the computation of Gamma, you must think of pairs of cases. Imagine four individuals. For each person, we know their income and education which has been categorized as low, medium, and high. The table below displays these values.