Hi everyone, I have some general questions about duration model and its implementation on Stata.

(1) Duration model looks at a subgroup of the population. For example, if we study the duration of unemployment, we are looking at only people who were unemployed during the year(s) of observation. Why is it seldom mentioned about sample selection problem in economics papers that use the model, or is it something that is not concerning at all? This is in contrast to the studies that use a Heckman model to correct for initial condition problem.

(2) If it is a problem, are there ways to implement on Stata discrete-time duration model that takes care of both unobserved heterogeneity and selection bias?

Many, many thanks indeed for your help!