How to estimate the standard deviation of the difference between two means?

[nadiaf]

Hello!

I've trying to estimate the SD of the difference between two means. I have the means, SD and n for each dataset. Below an example of how I have my dataset. I'd appreciate any help with this. Thanks!

ages	sex	n	mean A	SD A	mean B	SD B	Mean diff
19-30	males	882	7.45825	2.619444	6.2115	2.150556	-1.24675
19-30	females	897	5.58875	2.156296	4.666	1.774074	-0.92275
31-50	males	2077	7.591	2.546296	6.32325	2.089815	-1.26775
31-50	females	2288	5.83275	2.173704	4.86975	1.78963	-0.963

[Ksharp]

https://support.sas.com/kb/61/830.html

[PaigeMiller]

Your table seems to be just the summary statistics. If you have the raw data, then PROC TTEST does this easily, see figure 125.4 here: https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.4/statug/statug_ttest_gettingstarted02.htm

If you don't have the raw data, the formula for pooled standard deviation is given in many textbooks, web sites and even at Wikipedia, and I urge you to do a search to find the proper formula.