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Re: st: Count the number of changing string values
From
Ching Wong <[email protected]>
To
[email protected]
Subject
Re: st: Count the number of changing string values
Date
Fri, 14 Jun 2013 20:15:30 +0930
Hi Nick,
So what if -drug*- are numeric variables with value labels, how should
I change my Command?
Thanks!
Ching
On 14 June 2013 19:19, Nick Cox <[email protected]> wrote:
> Code that "doesn't work" but is not shown can not be commented on.
> Long structure (I prefer to avoid the word "format" here) is not
> essential for the problem as I understand it, but it is likely to be
> better for you for most analyses.
>
> The year in which people first said "No" is
>
> gen year = .
>
> qui forval j = 1999/2012 {
> replace year = `j' if Drug`j' == "No" & missing(year)
> }
>
> tab year
>
> So,
>
> 1. Everybody starts out with missing.
>
> 2. If they said "No" in 1999, -year- is changed to 1999
>
> 3. If they said "No" in 2000, -year- is changed to 2000, but only if
> -year- is missing (so values of 1999 are protected)
>
> and so on.
>
> You didn't explain your datatypes. If -drug*- are numeric variables
> with value labels, the syntax will differ accordingly.
>
> Nick
> [email protected]
>
>
> On 14 June 2013 10:20, Ching Wong <[email protected]> wrote:
>
>> I have the following data set:
>>
>> Id sex drug1999 drug2000 drug2001 drug 2001
>>
>> 1 F Yes No Yes Unknown
>>
>> 3 M No Yes Yes No
>>
>> 5 F Yes Yes Yes Yes
>>
>> 9 M Unknown Yes No Yes
>>
>> 10 F Yes No Yes No
>>
>> I would like to produce a count of to show the number of people who
>> quit each year, only count the first time they quit and do not care if
>> they change their status to ‘No’ again.
>>
>> What would be the command? I tried to change it to the long formal and
>> use the lag function, but it doesn’t work.
>
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