Alternative:
drop if substr(string(datedx),5,2) == "99" | substr(string(datedx),7,2) == "99"
todate datedx, pattern(yyyymmddd) format(%d) gen(datedx1)
Nick
[email protected]
Michael McCulloch
> Thanks Nick; this had just occurred to me.
> I was able to ferret out where the out-of-range days & months were:
>
> BEFORE
> . tostring datedx, replace
> datedx was double now str8
> . generate str4 dxyr1= substr(datedx,1,4)
> . generate str2 dxmo1 = substr(datedx,5,6)
> . generate str2 dxda1 = substr(datedx,7,8)
> . destring dx*, replace
> dxyr1 has all characters numeric; replaced as int
> dxmo1 has all characters numeric; replaced as byte
> dxda1 has all characters numeric; replaced as byte
> . gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
> (667 missing values generated)
>
> AFTER
> . tostring datedx, replace
> datedx was double now str8
> . generate str4 dxyr1= substr(datedx,1,4)
> . generate str2 dxmo1 = substr(datedx,5,6)
> . generate str2 dxda1 = substr(datedx,7,8)
> . destring dx*, replace
> . drop if dxmo==99
> (233 observations deleted)
> . drop if dxda==99
> (434 observations deleted)
> . gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
> *** no more missing; thanks for your help!***
> At 02:05 PM 1/11/2007, you wrote:
> >I am glad you are making progress, but if you have any "99"
> >for month and day, i.e. missing values encoded as such,
> >then -todate- has no way to work out the correct values.
> >So, your dates should still be missing in the same place.
> >It's just that -todate- doesn't squawk at you about them. At
> this point,
> >I am not sure that is a feature.
> >
> >Nick
> >[email protected]
> >
> >Michael McCulloch
> >
> > > Thanks Nick; using -todate-, now the missing values are no
> > > longer generated.
> > >
> > > . todate datedx , gen(datedx2) pattern(yyyymmdd)
> > > . format datedx2 %d
> > >
> > > Out of curiosity, I looked back at my previous method, and
> > > found that there
> > > were day and month ==99.
> > >
> > > . summarize dx??1
> > > Variable | Obs Mean Std. Dev. Min
> > > Max
> > >
> -------------+--------------------------------------------------------
> > > dxyr1 | 26806 1990.195 1.958295 1987
> > > 1993
> > > dxmo1 | 26806 7.269828 9.244575 1
> > > 99
> > > dxda1 | 26806 17.66037 15.60529 1
> > > 99
> > >
> > > >summarize dx??1
> > > >
> > > >to see which of the days, months, years variables are
> > > >out of range.
> > > >
> > > >Anyway, why are you doing it this way? Only a few days ago
> > > >a thread you started thrashed out the fact that -todate- from SSC
> > > >should be able to do it in one line.
> > > >
> > > >todate datedx, pattern(yyyymmdd) format(%d) gen(datedx1)
> > > >Michael McCulloch
> > > >
> > > > > I've converted a string date (yyyymmdd) to Stata
> format, using:
> > > > >
> > > > > . * convert datedx to Stata format
> > > > > . tostring datedx, replace
> > > > > datedx was double now str8
> > > > > . generate str4 dxyr1= substr(datedx,1,4)
> > > > > . generate str2 dxmo1 = substr(datedx,5,6)
> > > > > . generate str2 dxda1 = substr(datedx,7,8)
> > > > > . destring dx*, replace
> > > > > dxyr1 has all characters numeric; replaced as int
> > > > > dxmo1 has all characters numeric; replaced as byte
> > > > > dxda1 has all characters numeric; replaced as byte
> > > > > . gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
> > > > > (387 missing values generated)
> > > > > . format datedx1 %d
> > > > >
> > > > > However, search for missing values before & after my commands
> > > > > yields nothing:
> > > > > . list datedx if missing(datedx) in 1/10
> > > > >
> > > > > Where might the missing 387 values have originated?
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