# Search results

1. ### Clarifying the concept of a probability mass function

I am trying to understand what is the relationship between the concept of a probability mass function, and that of a probability measure. It seems to me that a probability mass function is simply a probability measure applied to a discrete random variable. Is that about right?
2. ### Trick question

The following question was posed to me : A person wants to compare between 2 versions of algorithms. He knows he has 100 False Negatives and wants the algorithms to find them. version 1 found 40 out of 100 False Negatives. version 2 found 90 out of 100 False Negatives. Is ver2 better?
3. ### Difference in differences estimation using a regression

Hello, Difference in difference estimation implies calculating (P2-P1)-(S2-S1). That would give the result of the treatment. It seems to me that the estimation is valid for a specific time point, time 2 at this example. I have read however (for example, at wikipedia), that DiD estimation can...