instead of:
by Personid Referraldate, sort: keep if _n == 1
this should be:
by Personid (Referraldate), sort: keep if _n == 1
which is to say, we want to sort on Referraldate within Personid, but then
pick the first observation in each stratum defined just by Personid, not
the first observation in each distinct Personid/Referraldate stratum.
The parentheses around Referraldate tell Stata to -sort- on it but not -by-
on it.
Phil
Date: Thu, 12 Feb 2004 11:21:26 +1030
To: [email protected]
From: Philip Ryan <[email protected]>
Subject: Re: st: Collapse
Jason
I am not sure you want the -collapse- command at all.
The command:
by Personid Referraldate, sort: keep if _n == 1
will -keep- the first observation of each Personid, and since you have
sorted on Referraldate within Personid, that first observation will be the
one with the earliest date. _n is Stata's built-in
current-observation-counter (I used SPSS a very long, long time ago and I
think it had a "seqnum" construct?).
I am assuming that your Referraldate variable is actually in Stata's
elapsed date form, so it can be treated as any other continuous numeric
variable. If not, check -help date- and especially -help datefcn-. Dates
are almost always best stored in Stata's elapsed form.
Phil
At 11:18 AM 12/02/2004 +1100, you wrote:
Dear all,
I need help regading the collapse command.
I want to collapse by personid, and keep the values for all variables
corresponding with the earliest(minimum) referralid. I want a final file
that has the first referral for each person including the date and agency
of that referral. The problem I am having is that the collapse is
defaulting to give the mean of the date and agency (or the minimum).
For instanace
Personid Referralid Referraldate(d.m.y) Referringagency
25 1 21.12.03 291
25 24 31.01.04 290
25 75 25.02.04 292
78 4 10.11.03 290
78 22 12.12.03 275
I want to collapse by the minimum value of referralid but I dont want the
minimum or mean value for referraldate or referringagency. I want the
values that correspond to the minimum referralid.
The result I want is:
Personid Referralid Referraldate(d.m.y) Referringagency
25 1 21.12.03 291
78 4 10.11.03 290
This is probably very easy, and i apologise for the trouble, but having
worked with SPSS for many years now, I am trying to find my way through
STATA logic as best as possible.
Regards
Jason Payne
____________________________________
Jason Payne
Violence, Property Crime and Drugs
Australian Institute of Criminology
GPO Box 2944 Canberra ACT 2601
E-mail: [email protected]
Tel +61 2 6260 9283 Fax +61 2 6260 9201
Visit the AIC homepage www.aic.gov.au
-----Original Message-----
From: Jason Payne
Sent: Thursday, 12 February 2004 9:56 AM
To: [email protected]
Subject: RE: st: Transformations
Thank you for your help,
Is there a way to list multiple cases that dont fit a standard expression
in the replace command. for example:
replace var1=1 if var2==1 or 3
I want cases 1 and 3 to have value 1 for var1, but not case 2 and rather
than writing the whole syntax twice, i would like to shorten it:
replace var1=1 if caseid==1
replace var1=1 if caseid==3
Any clues?
Regards
Jason Payne
____________________________________
Jason Payne
Violence, Property Crime and Drugs
Australian Institute of Criminology
GPO Box 2944 Canberra ACT 2601
E-mail: [email protected]
Tel +61 2 6260 9283 Fax +61 2 6260 9201
Visit the AIC homepage www.aic.gov.au
-----Original Message-----
From: Richard Williams [mailto:[email protected]]
Sent: Wednesday, 11 February 2004 12:53 PM
To: [email protected]; [email protected]
Subject: Re: st: Transformations
At 11:43 AM 2/11/2004 +1100, Jason Payne wrote:
>Dear STATAlistservers
>
>I am trying to transform data in variables. What is the equivalent STATA>
syntax for this SPSS command
>
>if (var1=2) var2=1.
Stata does things kind of backwards from SPSS:
gen var2 = 1 if var1==2
Note the ==
If var2 already exists, instead say
replace var2 = 1 if var1==2
But, what do you want when var1 does not equal 2? Missing? A 0-1
dichotomy? There may be some other ways to approach this, depending on whaty
our ultimate goal is.
>This syntax only works if you want to create a new variable, however in
>some cases I might with to modify an existing variable for one case
>only. This is particularly useful in cleaning string variables where
>there are spelling mistakes. In SPSS I would just type:
>
>if (caseid=1) stringvar='SPSS'.
>if (caseid=2) stringvar='STATA'.
replace stringvar="SPSS" in 1
replace stringvar="STATA" in 2
I'm assuming these are the first and second cases in your data. If not
necessarily so, and caseid is a variable in your data set, then try
replace stringvar="SPSS" if caseid==1
replace stringvar="STATA" if caseid==2
Or, just go in to the data editor and do it! Lot easier sometimes really.
-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
FAX: (574)288-4373
HOME: (574)289-5227
EMAIL: [email protected]
WWW (personal): http://www.nd.edu/~rwilliam
WWW (department): http://www.nd.edu/~soc
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Philip Ryan
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Philip Ryan
Associate Professor,
Department of Public Health
Associate Dean (Information Technology)
Faculty of Health Sciences
University of Adelaide 5005
South Australia
tel 61 8 8303 3570
fax 61 8 8223 4075
http://www.public-health.adelaide.edu.au/
CRICOS Provider Number 00123M
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