Please help me!!! about the interpreration of fixed effect model

[Chengyi Xu]

I got a stata command:
xtreg murdrate execrate c.execrate#c.execrate, fe vce(cluster countyid)

but I have no idea about how to interpret the results, for example, if the state command is reg y, x, I know that the result would be y=b0+b1x. How do I interpret THAT one?
THANK YOU!

[Joro Kolev]

The model you are fitting is
E(murdrate | execrate) = a + b*execrate + c*execrate^2

The marginal effect is
d[E(murdrate | execrate)]/d[execrate] = b+2*c*execrate
so you interpret the model from this expression.

A useful trick is to subtract say the mean of execrate, and then the estimated parameter on the main effect (b) will be the marginal effect evaluated at the sample mean.