If I have 100 subjects with 100 x and y values each can I simply combine them all together to get an r value? It is with the same variables (body temperature and heart rate). Obvioualy some inter-subject variability exists but collected under the same conditions.
It may be slightly more informative to plot data in a scatter plot and fit a linear regression model to these data, then test the model assumptions. This is fairly easy to do, even in MSExcel, but if not, yeah like Greta stated, "yes!" .