Marcel Pelgrom is a man, works for NXP. Measures lots of wafers looking for mismatch of transistors. Model for mismatch is named after him. Google is your friend!!!
When people talk about Pelgrom, they usually mean the mismatch model that says that the standard deviation of mismatch between two identical devices (close together) goes as A/sqrt(WL).
A is a process-dependent constant.
So essentially, devices match better as they get bigger.