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# Re: st: cumulative summation

 From James Bernard To statalist@hsphsun2.harvard.edu Subject Re: st: cumulative summation Date Tue, 26 Feb 2013 18:31:40 +0800

```Thanks Nick! I used -collapse- that you suggested...It was the easiest to do

Many Thanks,
James

On Tue, Feb 26, 2013 at 6:23 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> Also
>
> bysort group year : keep if _n == _N
>
> On Tue, Feb 26, 2013 at 9:05 AM, Nick Cox <njcoxstata@gmail.com> wrote:
>> It works, but does not do what you want. Many solutions, one of which is
>>
>> egen nties = max(ties), by(group year)
>>
>>
>> Nick
>>
>> On Tue, Feb 26, 2013 at 8:39 AM, James Bernard <jamesstatalist@gmail.com> wrote:
>>> 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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```