I want to find a data generating process implying homogeneous individual treatment effects.
Specifically, consider two potential outcomes $y_i^1$ and $y_i^0$.
The first one is the individual $i$'s (potential) outcome if she took a treatment.
and the second one is the individual $i$'s (potential) outcome if she did not take any treatment.
In this situation, I want to consider a data generating process under which the individual treatment effect, $y_i^1 - y_i^0$ is identical across all individual, that is $y_i^1 - y_i^0=y^1 - y^0$.
What data generating process yield the homogeneous individual treatment effects?