Hi I have used the amelia command from the Amelia R package. this gives me a number of imputed datasets. This may be a silly question, but i am not a statistician, but I am not sure how to combine these results to obtain the imputed dataset to usse for further statistical analysis. I have looked through the amelia and zelig manuals but still can not find the answer. This maybe because I dont understand the science behind it. Can anyone help Thanks in advance
Hi I have a dataset from biological data with forty samples whichh relate to four different treatments. Each sample has thousands of values but as usuual contains missing values I want to use EM to imput these missing values. I am doing tthis using amelia. Do I need to specify the various groups or can I just use the amelia command on the whole dataset (zz) together. zzAmelia <- amelia(zz[,-1], m=5) Also im not sure which value of m should be used Thanks in advance
Amit Patel-7 wrote:> > Hi > I have used the amelia command from the Amelia R package. this gives me a > number > of imputed datasets. > > This may be a silly question, but i am not a statistician, but I am not > sure how > to combine these results to obtain the imputed dataset to usse for further > statistical analysis. >The details depend on what you are doing with the data. Take the method you would use if there were no missing data, and apply it to each imputed data set. Average the estimates of interest from each imputed data set to get overall estimates. You then have to adjust the covariance matrix of the estimates to account for variability due to imputation. This is explained in various places, for example "Statistical Analysis with Missing Data" by Little and Rubin, and "Regression Modeling Strategies" by Harrell. Frank Harrell's rms package can do this combining of imputations for you. -- View this message in context: http://r.789695.n4.nabble.com/Help-with-Amelia-tp3160965p3161069.html Sent from the R help mailing list archive at Nabble.com.
Take a look at package 'mitools' and http://faculty.washington.edu/tlumley/survey/svymi.html for some examples in analyzing multiply-imputed survey data.> Hi > I have used the amelia command from the Amelia R package. this gives me > a number > of imputed datasets. > > This may be a silly question, but i am not a statistician, but I am not > sure how > to combine these results to obtain the imputed dataset to usse for > further > statistical analysis. I have looked through the amelia and zelig > manuals but > still can not find the answer. This maybe because I dont understand the > science > behind it. Can anyone help > > Thanks in advance > > > > > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code.