Hello R users!
I have several data frames where some of the variables have many missing 
observations. For example, Q1 in one of my data frames has over 66% of its 
observations missing. I have tried imputation with mice but it does not work 
for all the data frames and I get the following message or a similar message to 
this:
 iter imp variable
  1   1  Q1  Q2  Q3  Q4  Q5  Q6  Q7  Q8  Q9  Q10  Q11  Q12  Q13  Q14  Q15  Q19  
Q36  Q47  Q52  Q79  Q80  Q94  Q97  Q104  Q108  Q122  Q131  Q134  P1  P2  P3  P4 
 P5  P6Error in solve.default(xtx + diag(pen)) : 
  system is computationally singular: reciprocal condition number = 1.83044e-16
In addition: Warning messages:
1: In sqrt((sum(residuals^2))/(sum(ry) - ncol(x) - 1)) : NaNs produced
...
7: In sqrt((sum(residuals^2))/(sum(ry) - ncol(x) - 1)) : NaNs produced
Note: warnings 2 to 6 suppressed by me.
I would like to try a different approach where I delete the variables that have 
more than 50% missing observations from the data frame (well, the actual 
percentage might change). I have already deleted from the data frame the 
variables that were all missing and for this I used the following code, which 
was kindly suggested by one of you:
## Data frame after removing any blank columns:dfQ <- dfQtemp[ , 
sapply(dfQtemp, function(x) !all(is.na(x)))]
 Any ideas or suggestons for deleting variables with partially missing data? 
Thanks and have a great weekend!
Rita ===================================== "If you think education is 
expensive, try ignorance."--Derek Bok


                                          
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