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Re: st: St: Dropping variables with mostly missing values


From   Nick Cox <[email protected]>
To   "[email protected]" <[email protected]>
Subject   Re: st: St: Dropping variables with mostly missing values
Date   Sat, 8 Feb 2014 00:00:38 +0000

Good solutions to this came from Jeph Herrin, Amirsa and Richard Goldstein.

Meanwhile, anyone interested in -dropmiss-, which doesn't do this,
should please note that it comes from the Stata Journal, not SSC.

Nick
[email protected]


On 7 February 2014 20:40, Jeph Herrin <[email protected]> wrote:
> To drop all variables missing more than 80% of the time:
>
> foreach V of varlist _all {
>         count if !mi(`V')
>         drop if r(N)/_N < 0.2
> }
>
>
> This works for string and numeric variables. Change 0.2 to whatever level
> you want.
>
> hth,
> Jeph
>
>
>
>
>
> On 2/7/2014 3:11 PM, Eric M. Uslaner wrote:
>>
>> I know that this has been discussed before, but a long search doesn't find
>> a solution for me (my own fault in searching, most likely).
>>
>> I have a data set (not my own) with 161 cases over a long time period.
>> But  most of the variables are largely made up of missing values
>> (information wasn't available a long time ago).  I have used Nick Cox's
>> dropmiss (from SSC) to drop variables with all missing values.  But a large
>> number of variables remain with few observations.  I would like to delete
>> any variable with fewer than 20 cases.  But I can't figure out how to do
>> this (especially since I have a large number of variables, most of which
>> have very few cases).  Any help would be appreciated.
>>
>> Ric Uslaner
>>
>>
>>
>>
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