2-Way Contingency Tables

Two-way contingency tables are used to compare two QUALITATIVE variables, such as gender versus political party, or uniform shirt color versus uniform pants color. We make the table and then find the totals for all variables by counting the number of observations in each.

This is an example of a 2-way contingency table. We can find the marginal distributions by looking to the row/column totals and dividing by the grand total. For example, if we wanted to find the marginal distribution of yes event observed, we would do 8/28. A conditional distribution is conditioned on one of the variables within the table. For example, if we said "find the conditional distribution of no event observed conditioned on yes event forecasted, we would do 16/18. Usually, we write these answers as a percentage rather than a fraction.

For five extra bonus points on your next problem set, find and interpret the conditional distribution of yes event forecasted conditioned on no event observed. I will take your submissions up until this Friday, August 31st.