st: dbetafit vs margins

[Cristina Sechel <cs998@york.ac.uk>]

I'm using betafit to estimate a model with a proportional dependent
variable and I want to obtain various marginal effects. At first I used
dbetafit to obtain the marginal effects of the continuous independent
variables, but the output shows up in scientific notation and that is
problematic for me because most of my estimates are very small and they get
cut off.

I then decided to use margins because I like the format of the output a lot
better and I can see the estimate to many more decimal points. I also like
that I can use marginsplot after margins and it's just overall a more
versatile command than dbetafit, so I'd rather use margins.

But the results of dbetafit and margins do not exactly match and I don't
understand why. For continuous variables, the estimates are the same but
the standard errors are different. And for dummy variables, the estimates
do not match at all. Does anyone know why this is happening?

The dbetafit code I used is:

dbetafit, at(D1 0 D2 0)

The margins code is:

margins, dydx(*) at((mean) X1 X2 X3 (zero) D1 D2)

where X1, X2, X3 are the continuous independent variables, and D1, D2 are
the dummies.

Thanks,
Cristina
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