If you start with a data table with three or more Y columns, you can ask Prism to compute the correlation of each column with each other column, and thus generate a correlation matrix.
The results appear on three pages:
•The correlation coefficient r (or rs). This is computed for each pair of variables and doesn't not account for other variables. Prism does not compute a partial correlation coefficient.
•The P value (two-tail) testing the null hypothesis that the true population correlation coefficient for that pair of variables is zero.
•The number of XY pairs. This might not be the same for all pairs of variables if some data are missing.
You can make a heat map from any of these three results pages. From the page, click New and choose Graph of existing data. Choose a Grouped graph, then choose the Heat Map tab.