Title: Column percentages
Course: UGQuants (SSPS) > Section: Associations Between 2 Variables

Column percentages

Column percentages show, for each value of the variable shown in the columns, the % of cases that fall into each category of the variable shown in the rows. So, e.g. in table 2 the figure 13 indicates the percentage of men who have contacted a politician.

There are at least two other ways of thinking about column percentages that might help you grasp them.

First, we can think of column percentages as showing a separate frequency table of the dependent variable for each value of the independent variable. So we could understand table 2 as showing two frequency tables on contacting politicians: one for men and one for women. The same principle can be applied to larger tables: if e.g. there are 5 values for the independent variable, then we can understand the contingency table as containing 5 separate frequency tables, one for each value of the independent variable.

Second, column percentages should always sum to 100% when we add them up reading down the column: e.g. in the column in table 2 showing whether or not women have contacted a politician, 17+83=100 (sometimes, where percentages have been rounded, these may sum to very nearly but not exactly 100 ). Whilst this might seem obvious but in fact offers a very useful way of resolving the very common confusion between column and row percentages.