I think this can be approached also in
an assumption-free way.
1. use -edit- or -input- to add a block
of observations with a bogus zip code and
all years exemplified.
2,
fillin zip year
replace count = 0 if _fillin
3.
delete the bogus observations
Nick
[email protected]
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of McKenna,
> Timothy
> Sent: 25 May 2004 22:11
> To: [email protected]
> Subject: st: RE: RE: "imputing" missing observations
>
>
> If you are not sure about whether each year is represented:
>
> * find problems
> gen elapsed_years = (year - year[_n-1]) if (zip == zip[_n-1])
> expand elapsed_years
> sort zip year
> * replace the now bogus counts
> replace count = 0 if ((elapsed_years > 1) & (year ==
> year[_n-1]) & (zip == zip[_n-1]))
> * get the year right
> replace year = (year[_n-1] + 1) if (zip == zip[_n-1])
>
> This does assume that the first year and last year for each
> zip code are observed with non zero counts. Otherwise you
> would not be able to tell it is missing from the setup of the data.
>
> -Tim
>
> -----Original Message-----
> From: Nick Cox [mailto:[email protected]]
> Sent: Tuesday, May 25, 2004 4:49 PM
> To: [email protected]
> Subject: st: RE: "imputing" missing observations
>
>
> So long as 1989 is a value for some other
> zip, you can
>
> fillin zip year
> replace count = 0 if _fillin
>
> Nick
> [email protected]
>
> Heather Taffet Gold, PhD
>
> > I've been looking all around, asking around, etc, and I can't
> > seem to find
> > out how to create new observations within my dataset.
> >
> > Here are the specifics of my problem:
> > I have counts of cases by zip code and year (one observation
> > with count for
> > each zip, and year). It happened that I ended up with "missing"
> > observations if the count of cases was zero in a year, so my
> > data look
> > something like this
> > zip year count
> > 06010 1986 1
> > 06010 1987 2
> > 06010 1988 2
> > 06010 1990 7
> > ...
> >
> > How would I create a new observation for this zipcode in 1989
> > that has a
> > count of 0? I need to be able to create some lagged variables
> > by year and zip.
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
