Near the end of my first statistics class, I was introduced to the concept of a hypothesis test: given two sample sets, determine the probability that they were drawn from the same population. If this is less than your desired p-value (typically 5% or less, depending on your field), you can reject the [null-hypothesis][1] and accept the alternative hypothesis that the two samples are indeed from different populations.
This was presented to me in the context of social sciences, but it comes up in