st: interpretation of interaction in semi-logarithmic models

[Shehzad Ali <sia500@york.ac.uk>]

Hi listers,

I was wondering if someone can help with the interpretation of coefficient 
on the interaction term in a semi-logarithmic model. Here is my model:

log(y) = x1 log(x2) x1*log(x2) x3 x4

Here x1 is a dummy variable for program participation, x2 is income and y 
is cost.

Any help would be appreciated.

Many thanks,

Shehzad
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