Nick, I apologize if I was harsh in my response.
Justin White
-----Original Message-----
From: White, Justin
Sent: Thursday, August 24, 2006 11:15 AM
To: '[email protected]'
Subject: RE: RE: RE: Merge two long datasets? and re: stopping loops
The capitalization happened in the email (auto correct). I did not
intentionally capitalize the commands. Isn't this a bit petty?
The advice I provided is how I would personally do it. Everyone's style
is different. There may be hundreds of ways to get the same thing
accomplished.
Justin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Nick Cox
Sent: Thursday, August 24, 2006 11:08 AM
To: [email protected]
Subject: st: RE: RE: Merge two long datasets? and re: stopping loops
The main advice here is correct.
However, the advice on creating
a new variable suggests an unnecessary change to
your data. There is absolutely no need to apply
-tostring- (which normally would need to be reversed
for much subsequent analysis). -tostring- should be applied
if and only if there is some numeric variable that
really should be string for ever more.
egen group = group(momid year)
would be a better method of creating a single identifier
if you needed it -- but I don't think you do.
In addition, I don't think it helps anyone if commands
with names like
sort
tostring
gen
are capitalised. Finally, for "STATA" read "Stata".
Nick
[email protected]
White, Justin
> Yes. You can merge using two separate variables. Look in the STATA
> command help under merge. There is an example where multiple
> variables
> are referred to. You must remember that the variables you
> use to merge
> must be how your data set is sorted. For instance, it you
> want to merge
> using momid and year you must make sure your two data sets
> are sorted by
> momid and year:
>
> Sort momid year
>
> Also, you can consider creating a new variable. For instance:
>
> Assuming the momid and year variables are string variables
> Gen str prim_key = momid+year
>
> If they are not strings, you must convert them to a string:
> Tostring momid year, replace
> Gen str prim_key = momid+year
Claire M. Kamp Dush
> Thanks Scott for the tip. I did make a mistake in copying my
> data, so
> thanks for pointing that out. I have one follow-up and one new
> question:
>
> First, there is the continue command for breaking out of
> loops. I just
> found it in the Stata 9 Programming manual. So, anyone who
> is trying to
>
> figure that out might want to check out that manual [P] under
> continue.
> I
> wish I had found it earlier.
>
> Second, before I found that command, I did as you advised, and managed
> to
> merge the data together beautifully. However, this poses another
> question:
>
> Is it possible to merge on two variables? That is, can I merge two
> datafiles by momid AND by year at the same time? Or, is it always
> necessary to convert both datasets back to wide form, then
> merge, then
> reconvert the new dataset to long. This is what I did. I have done
> some
> digging to try to figure out how to merge long datasets, and I have
> always
> come up short.
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