# Internals: Left truncation

A short note on how mrds deals with left truncation.

• process.data actually performs the truncation on the data.
• during fitting:
• evaluations of the detection function are calculated as “normal”, i.e. $g(x,z;\theta)$
• integration is carried out over the left to right truncation interval, i.e. $\int_\text{left}^\text{right} g(x,z;\theta) dx$