[R] replacing missing values with row average

[Bert Gunter]

Warning: This is not a helpful answer. Actually, it's a question: Why
do you want to do this? Replacing missing values with row or column
averages and then analyzing the data as if the missing values were not
there is a dangerous thing to do it can produce biased estimates and
understate the true error, likely resulting in biased inference. Of
course, this depends on the specifics (how many are missing and
where).

R has a lot of built-in capabilities for handling missing values. I
agree: it's not easy stuff. Nor do you necessarily need to get that
complicated: Maybe your scheme is perfectly adequate for your
situation. I just wanted to caution you think about this carefully if
you aren't aware of the possible problems and haven't already done so.

-- Bert



On Sun, Feb 27, 2011 at 3:25 PM, Daniel M. <danielmessay at yahoo.com> wrote:
> Hello,
>
> I have some dataset, which i read it from external file using the (data <-
> read.csv("my file location")) and read as a dataframe
>
>> is(data)
> [1] "data.frame" "list"       "oldClass"   "vector"
> but i have also converted this into a matrix and tried to apply my code but
> didnt work.
>
> Anyways, suppose i have the following data.
>
>
>    data <- as.data.frame(matrix(rnorm(100), nrow = 10))
>
> And let's put some missing values
>
>    data[sample(1:10, 3), sample(1:10, 3)] <- NA
>
> I want to replace all NA's by row averages or column averages of my matrix.
>
> I tried to use(with my original data matrix)
>
>    data[is.na(data)] <- rowMeans(data, na.rm = TRUE)
> But got an error message of
>
>       Error in rowMeans(data, na.rm = TRUE) : 'x' must be numeric
> Then I converted  data<- as.matrix(data)
>                  data<- as.numeric(data)
> And applying my code
>
>     data[is.na(data)] <- rowMeans(data, na.rm = TRUE)
>
> Error message
>
>
>      Error in rowMeans(data, na.rm = TRUE) :
>  'x' must be an array of at least two dimensions
>
> Then again i tried to convert it into Arrays....but the errors continues....
>
> I Also tried the code
>
>    data[is.na(data)] <- apply(data,1,mean)
>
> But still didnt work out.
>
> Can anyone pls help me as to how to fix it and get out of this, please?
>
> Thank you very much
>
> Daniel
>
>
>
>        [[alternative HTML version deleted]]
>
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>



-- 
Bert Gunter
Genentech Nonclinical Biostatistics