What's joint frequency?

A joint frequency is how many times a combination of two conditions happens together. For example:

Pet owners (condition 1) who are women (condition 2),

Democrats (condition 1) who are married (condition 2),

Joint relative frequency is the ratio of the frequency in a particular category and the total number of data values. The purple cells on our table are all joint frequency numbers. It is called joint frequency because you are joining one variable from the row and one variable from the column.