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Re: st: cumulative summation


From   James Bernard <jamesstatalist@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: cumulative summation
Date   Tue, 26 Feb 2013 16:39:27 +0800

Thanks Nick,

I have missing values in my list, so it seems that the command is not
working, because it sets many of the values to . (missing).

I gave you the simplifies version. In fact, I am using loops and
macros to do this

Then, instead would it be possible to write a comand that can detect
that for firm A in 1990, 2 is the larger one.

Alternatively, would it be possible to ask the program to keep only
the last observation of every group (a group defined by firm and year)

Thanks a gain,
James


On Tue, Feb 26, 2013 at 3:49 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> bysort firm year (ties) : replace ties = ties[_N]
>
> Nick
>
> On Tue, Feb 26, 2013 at 7:08 AM, James Bernard <jamesstatalist@gmail.com> wrote:
>
>> I have used the sum function to calculate a variable in  a panel data.
>>
>> Firm        Year      ties
>> -----------  ----------    -------
>> A             1990      1
>> A             1990       2
>> A             1991       1
>> B             1990       0
>> B             1990       1
>> B             1990        3
>> C             1990        0
>> C             1991        0
>> C             1992        0
>>
>> The issue is that the variable ties which is the number of ties a firm
>> has formed in a year is a cumulative sum of something and, therefore,
>> for a company like A the final number of ties in year 1990 should be
>> 2. I need the program to write the same number (final value of the
>> cumulative sum) instead of 1.
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