[R] value labes Stata vs factors

[Peter Dalgaard]

Rob Bakker wrote:
> Dear Sir/Madam,
> I converted my Stata Rgenmetvl.dta file with read.dta succesfully in R's
> Rgenmetvl.Rdata. However, factors give problem in certain calculations,
> e.g.:
>> mean(Rgenmetvl$sex)
> [1] NA
> Warning message:
> In mean.default(Rgenmetvl$sex) :
>   argument is not numeric or logical: returning NA
> 
> What can I do?

Factors can't be averaged. You can average a score based on a factor 
though, as in

mean(c(1,2)[Rgenmetvl$sex])

or

mean(as.numeric(Rgenmetvl$sex))

These do the same thing, but the former allows you more control of the 
scores asssigned. Notice that the values need to be in the order of 
levels(Rgenmetvl$sex).

Alternatively, use read.dta(...., convert.factors=FALSE) to get a 
version of data containing the original numeric values.

-- 
    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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