Let's say you got a sample. If you are calculating the mean of the sample, we are saying that you calculated the empirical mean (
moyenne empirique). This is because you used the values instead of the theory.
- empirical moments (mean, ...)
- empirical quantiles
- order statistic (
statistiques de rang/d'ordre)
The main idea is that you got a vector of size $n$ like $n$ observations and after the empiric estimation, you got a vector of size $1$. You may ask yourself, how much information did you lose? Because sometimes, you really lost a lot of information.