Re: [R] propensity score adjustment using R

2008-10-06 Thread Marc Flockerzi
the Matching() package by Jasjeet Sekhon does propensity score matching in a very user friendly way. (as you said you don't want to reinvent the wheel...) just feed it with the fitted values from a glm model (fitted$myglmmodel). afaik, you may additionally match on some covariates directly. HTH m

Re: [R] propensity score adjustment using R

2008-09-18 Thread Frank E Harrell Jr
ran2 wrote: Frank E Harrell Jr wrote: That is a high variance procedure as compared with covariate adjustment using the propensity score, or stratification. Frank Harrell Ah, wait what if I got very high dimensional X ? Even with 20 binary covariates i would end up with more than 1 mil

Re: [R] propensity score adjustment using R

2008-09-18 Thread ran2
Ben Domingue wrote: > > I'm not quite sure what you mean. If all you need is propensity > scores to run an IPW analysis, the fitted values should work. Having > many binary covariates shouldn't be a problem, the whole point of the > propensity score is boiling down many dimensions to a single

Re: [R] propensity score adjustment using R

2008-09-18 Thread Ben Domingue
I'm not quite sure what you mean. If all you need is propensity scores to run an IPW analysis, the fitted values should work. Having many binary covariates shouldn't be a problem, the whole point of the propensity score is boiling down many dimensions to a single one. I use matchit() for my psm n

Re: [R] propensity score adjustment using R

2008-09-18 Thread ran2
Frank E Harrell Jr wrote: > > > > That is a high variance procedure as compared with covariate adjustment > using the propensity score, or stratification. > > Frank Harrell > Ah, wait what if I got very high dimensional X ? Even with 20 binary covariates i would end up with more than 1 m

Re: [R] propensity score adjustment using R

2008-09-18 Thread ran2
Frank E Harrell Jr wrote: > > That is a high variance procedure as compared with covariate adjustment > using the propensity score, or stratification. > > Frank Harrell > Yes, I guess the foo$fitted.values was the syntax i missed. I know this method is not optimal and that it yields high va

Re: [R] propensity score adjustment using R

2008-09-18 Thread Frank E Harrell Jr
Bunny, lautloscrew.com wrote: Hi all, i am looking to built a simple example of a very basic propensity score adjustment, just using the estimated propensity scores as inverse probability weights (respectively 1-estimated weights for the non-treated). As far as i understood, MLE predictions o

Re: [R] propensity score adjustment using R

2008-09-18 Thread Ben Domingue
Bunny, lautloscrew.com lautloscrew.com> writes: ix of some covariates. > > I wonder right now if te glm respectively summary(glm(...)) puts out > something comparable to ML estimates that can be used as the estimated > pscores, in such a way that there is one value for every observation. >

[R] propensity score adjustment using R

2008-09-18 Thread Bunny, lautloscrew.com
Hi all, i am looking to built a simple example of a very basic propensity score adjustment, just using the estimated propensity scores as inverse probability weights (respectively 1-estimated weights for the non-treated). As far as i understood, MLE predictions of a logit model can direct