Typically, economists do not care about the estimated coefficients from binary dependent variable models, but do care about their marginal effects. There does not seem to be a package in R which performs this calculation as simply as the mfx command -- which correctly handles factor variables and estimates the standard errors accurately -- as in Stata. I wanted to write a blog post containing some simple functions I have written which offer an easy solution to this issue. However, this post would have been too long. Instead I wrote a short paper which can be downloaded at the following link. Hopefully this paper will be helpful to researchers looking to implement marginal effect calculations and also to those interested in a simple basic explanation of where these figures come from when they are produced by other software packages such as Stata.
Abstract
This paper outlines a simple routine to calculate the marginal effects of logit and probit regressions using the popular statistical software package R. I compare results obtained using this procedure with those produced using Stata. An extension of this routine to the generalized linear mixed effects regression is also presented.
If you are not inclined to use this approach you could use the simple scale factors derived in this little piece of mine
ReplyDeletehttp://www.ucd.ie/t4cms/WP09.09.pdf