[R] error in NORM lib

[Leo Gürtler]

Dear alltogether,

I experience very strange behavior of imputation of NA's with the NORM 
library. I use R 2.2.0, win32.
The code is below and the same dataset was also tried with MICE and 
aregImpute() from HMISC _without_ any problem.
The problem is as follows:

(1) using the whole dataset results in very strange imputations - values 
far beyond the maximum of the respective column, > 200%! and this is 
reproducible and true for the whole set of imputed NAs
(2) using just part (i.e. columns) of the dataset results in the fact 
that some NAs are not imputed at all, i.e. NAs are still in the dataset 
- but there is neither a warning nor an error
(3) data.augmentation with da.norm() fails, but not after the first 
step, mostly 3-5 steps are ok, then it stops (see below)

The dataset is from educational research and should be almost normal 
distributed (slight deviations, but not really that heavy to explain the 
strange results).
I don't understand this, because the dataset works well with MICE and 
aregImpute() and other statistics _and_ I checked the manpages and it 
does not seem that the calls are wrong.
Thus, either it depends on the dataset (but why?) or it is maybe a bug.

I appreciate every help,

thanks,

leo gürtler

<---snip--->

library(norm)
rngseed(1234)
load(url("http://www.anicca-vijja.de/lg/dframe.Rdata"))   # load object 
"dframe"
dim(dframe)
apply(dframe,2,function(x) sum(is.na(x))) # check how many NAs in the 
dataset
#dframe <- 
subset(dframe,select=-c(alter,grpzugeh,is1,is4,is6,klassenstufe,mmit,vorai,vorap,voras,vorkf,vorsg,vorvb))
s1 <- prelim.norm(dframe)
s1$nmis   # re-check of NAs should be identical to above
s2 <- prelim.norm(dframe[,1:32])# see below -> still NAs are available - 
_not_ imputed
thetahat1 <- em.norm(s1)
theta1 <- da.norm(s1,thetahat1,steps=20,showits=TRUE)  # error:
                                                       # Steps of Data 
Augmentation:
                                                       # 
1...2...3...4...5...6...7...8...Fehler: NA/NaN/Inf in externem 
Funktionsaufruf (arg 2)
thetahat2 <- em.norm(s2)
( imputed1 <- imp.norm(s1,thetahat1,dframe) )    # very strange imputed 
values
                                                 # almost >200% to big 
than expected
( imputed1.1 <- imp.norm(s1,theta1,dframe)  )    # not possible - 
because da.norm gives no result!
( imputed2 <- imp.norm(s2,thetahat2,dframe) )    # still NAs in the matrix

# visualize the strange values
par(mfrow=c(2,1))
hist(dframe,prob=TRUE)      # histogramm data set with NAs - original values
lines(density(na.omit(dframe)))
hist(imputed1,prob=TRUE)   # histogramm of dataset with imputed values
lines(density(imputed1))


</---snip--->