Re: [R] logistic regression in an incomplete dataset

2010-04-06 Thread Desmond Campbell
Of Desmond D Campbell Sent: Monday, April 05, 2010 3:19 PM To: Emmanuel Charpentier Cc: r-help@r-project.org; Desmond Campbell Subject: Re: [R] logistic regression in an incomplete dataset Dear Emmanuel, Thank you. Yes I broadly agree with what you say. I think ML is a better strategy than complete case

Re: [R] logistic regression in an incomplete dataset

2010-04-06 Thread Desmond Campbell
Dear Thomas, Thanks for your reply. Yes you are quite right (your example) complete case does not require MCAR, however as well as being a bit less robust than ML it is throwing away data. Missing Data in Clinical Studies, Geert Molenberghs, Michael Kenward, have a nice section in chapter 3

[R] logistic regression in an incomplete dataset

2010-04-05 Thread Desmond D Campbell
Dear all, I want to do a logistic regression. So far I've only found out how, in a dataset of complete cases. I'd like to do logistic regression via max likelihood, using all the study cases (complete and incomplete). Can you help? I'm using glm() with family=binomial(logit). If any covariate in

[R] logistic regression in an incomplete dataset

2010-04-05 Thread Desmond Campbell
Dear all, I want to do a logistic regression. So far I've only found out how to do that in R, in a dataset of complete cases. I'd like to do logistic regression via max likelihood, using all the study cases (complete and incomplete). Can you help? I'm using glm() with family=binomial(logit).

[R] logistic regression in an incomplete dataset

2010-04-05 Thread Desmond Campbell
Dear all, I want to do a logistic regression. So far I've only found out how to do that in R, in a dataset of complete cases. I'd like to do logistic regression via max likelihood, using all the study cases (complete and incomplete). Can you help? I'm using glm() with family=binomial(logit).

Re: [R] logistic regression in an incomplete dataset

2010-04-05 Thread JoAnn Alvarez
Hello Desmond, The only way to not drop cases with incomplete data would be some sort of imputation for the missing covariates. JoAnn Desmond Campbell wrote: Dear all, I want to do a logistic regression. So far I've only found out how to do that in R, in a dataset of complete cases. I'd

Re: [R] logistic regression in an incomplete dataset

2010-04-05 Thread Emmanuel Charpentier
Dear Desmond, a somewhat analogous question has been posed recently (about 2 weeks ago) on the sig-mixed-model list, and I tried (in two posts) to give some elements of information (and some bibliographic pointers). To summarize tersely : - a model of information missingness (i. e. *why* are

Re: [R] logistic regression in an incomplete dataset

2010-04-05 Thread Desmond D Campbell
Dear JoAnn, Thank you very much for your reply. If that is the case I am surprised. I would have though ML could incorporate study cases with some missingness in them. Furthermore I believe ML estimates should generally be more robust than complete case based estimates. For unbiased estimates I

Re: [R] logistic regression in an incomplete dataset

2010-04-05 Thread Desmond D Campbell
Dear Emmanuel, Thank you. Yes I broadly agree with what you say. I think ML is a better strategy than complete case, because I think its estimates will be more robust than complete case. For unbiased estimates I think ML requires the data is MAR, complete case requires the data is MCAR

Re: [R] logistic regression in an incomplete dataset

2010-04-05 Thread Thomas Lumley
On Mon, 5 Apr 2010, Desmond D Campbell wrote: Dear Emmanuel, Thank you. Yes I broadly agree with what you say. I think ML is a better strategy than complete case, because I think its estimates will be more robust than complete case. For unbiased estimates I think ML requires the data is MAR,