Bookmark and Share

Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, statalist.org is already up and running.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: st: calculating cumulative values of other observations


From   Eric Booth <eric.a.booth@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: calculating cumulative values of other observations
Date   Sat, 7 Apr 2012 13:09:35 -0500

<>

On Apr 7, 2012, at 9:42 AM, KOTa wrote:

> thanks Erik, Nick
> 
> both ways work on this sample, and i managed to adjust for a real database also.
> 
> few followup question:
> 
> 1. Eric, any specific reason why you convert time into date format? I
> used it without conversion and it looks fine.
> Also on real data your solution somehow goes into infinite loop after
> finishing all calculations.
> 
I don't know how you edited the code, so I don't know how you produced an infinite loop?  It certainly doesn't do that with the example I gave you.  Also, I created a time/date format version of "date" just out of habit, I find that it makes data management easier.  If you don't need/want it, then skip it.


> 2. Nick, the solution you proposed with "sum" was the one i tried
> initially. The problem is that in real data I have 2 columns for date
> (start_date end_date) and i want to compare start_date [_n] >=
> end_date[all previous]
> Eric's solution works longer, but i could adjust it to work with
> different date columns.
> your solution is works much faster in case there is one date column,
> but i could not figure out how to do the same with 2 different
> columns.

El día 7 de abril de 2012 04:08, Nick Cox <njcoxstata@gmail.com> escribió:
> Why not
> bysort id activity (time): gen priorhrs = sum(time) - time
> Nick


Nick's -sum- solution does work (and is more straightforward than my -replace line)  with a slight tweak - changing the first "time" to "date2" (if you create the time/date var from my example).  Also, if you are using the same variable names from your original example you'd change "time" to "hours".  Adding this to my example works:

  bysort ID activity (date2): gen njc = sum(hours) - hours


Adapting mine and Nick's code to your "real" dataset is another issue completely - if you cannot figure how to adapt our tips to your data/code, then you should post a data & code example/question that is closer to reality.


- Eric
__
Eric A. Booth
Public Policy Research Institute
Texas A&M University
ebooth@ppri.tamu.edu
Office: +979.845.6754



*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index