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Re: st: group classification
From
"Ellen Kisker" <[email protected]>
To
[email protected]
Subject
Re: st: group classification
Date
Wed, 26 Jan 2011 17:32:00 -0600
Compost
tried to send a message about that but guess it didn't go thru
atmidway now & ready to be home
hope u had a good day
-----Original Message-----
From: Jurgen Sidgman <[email protected]>
Subj: st: group classification
Date: Wed Jan 26, 2011 4:33 pm
Size: 1K
To: [email protected]
Hi all,
I have what I thought it was a simple problem but has turned out to be a head age. I have a dataset of company names and transaction dates. What I need to do with it is as follows:
For each company, at the end of every april of each year, I want to verify that in the prior six months the company has at least one transaction. If the company has a transaction between november of the prior year and April of the current year I code it with a 1. If the company does not have a transaction within that period, regardless of having transactions in other months (lets say september) I code it with a 0.
I keep getting false positives because I have companies that have transactions in lets' say november and december of last year, no transactions on this year, and again transactions in january of next year. Then, what i get is that i am able to set to one last year and the next year, but I get a zero on the current year, which is not appropriate.
My code follows
. use "dataset.dta", clear
. drop if month(transdate) >= 5 & month(transdate) <= 10
. drop if month(transdate) < 11 & year(transdate) == 2004
. drop if month(transdate) > 4 & year(transdate) == 2008
. save "cross_section.dta", replace
. gen transyear = year(transdate)
. Keep compname transyear
. duplicates drop
. gen prior6 = 1
. snapshot save, label("Snapshot 1")
. use "dataset.dta", clear
. drop if month(transdate) < 11 & year(transdate) == 2004
. drop if month(transdate) > 4 & year(transdate) == 2008
. gen transyear = year(transdate)
. save "cross_section.dta", replace
. merge 1:m cusip form4 transyear using "cross_section.dta"
Obviously merging using the year in the key does not work, but I am out of ideas for the moment. Can anyone help?
Thank you!
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