# Thread: t-test

1. ## t-test

i was wondering, why exactly does the t-test work well for small samples? is there an explanation for this?

also, is there an explicit formula for the paired t-test?

2. The t-test is used when we don't know sigma and need to estimate it with S.
In small samples we need the data to be from a normal distribution in either case.
When the sample size is big then we can approximate the test stat via the central limit theorem