# Paired-t test for comparing two subgroups selected from the same underlying population?

Say I have a total population of N=100. Algorithm #1 is based on some predictors and it selects n1=10 subjects (i.e., subgroup #1). Algorithm #2 is based on another set of predictors and it selects n2=50 subjects (i.e., subgroup #2) from the same original population (N=100).

Some of these selected subjects appear twice in both Algo #1 and Algo #2 derived subgroups, while each subgroup also has its own unique subjects.

Now, each subgroup has an average age, am I correct to use paired t-test to test for statistical difference? Or should I use a different test?

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Edits:

What I want to test for is whether the mean age of subgroup #1 is statistically different (at p=0.05) than the mean age of subgroup #2 (considering the fact that some subjects appear in both subgroups, while others only appear in either subgroup #1 or subgroup #2).

• N=100, N=10, N=50, N=100. We have 26 letters. – user158565 Oct 30 '18 at 17:48
• What are you trying to test for? Your question seems to be missing the detail of what you want to know from or about the samples or population or algorithms. – Michael Lew Oct 30 '18 at 19:32