Dear list,
I am trying to estimate a difference-in-difference model with panel
data, i.e. Yist (where s indicates the treatment/control group) as a
function of a dummy Dist equal to 1 for the treatment group after the
treatment occurs, and 0 otherwise.
The basic steps I follow to do this are:
tsset id_var t_var
xtreg Yist Dist, i(id_var) fe
However, when I use tsset, I receive the message "repeated time values
in sample" because units i are called the same in both the treatment
and control groups - e.g. same firm in country A (treatment) and
country B (control).
Is there a way to fix this, other than assigning a different id to
each unit in the treatment and control groups? Many thanks,
fiorenzo
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