I am trying to know if there is another way of adding two data sets together and then obtaining the standard deviation of the combined set. Currently, these data sets have equal numbers of subjects. What I am doing is putting all the results together and then simply getting the standard deviation from the combined set. There is no difference between the two sets, just that one experiment was performed at a later time but with the same conditions (i.e. I just wanted to increase the total population count for better statistics).
My questions is: is there a more correct way of doing this than adding the sets together? or should I analyze each data set individually? if so then how could I get a single standard deviation value for the entire population?
Thank you very much for your help!
Best regards, JohnWick