Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: How to drop low frequency patterns from panel data
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re: st: How to drop low frequency patterns from panel data
Date
Fri, 3 Feb 2012 09:35:06 +0000
-xtpatternvar- is a user-written command from SSC. Please remember to
explain where user-written programs you refer to come from.
bysort pattern : drop if _N < 20
is I think what you seek.
Nick
On Fri, Feb 3, 2012 at 9:22 AM, Kim Peeters <[email protected]> wrote:
> I have an unbalanced panel data set. The yearly data spans a period of almost twenty years. However, most subjects only participated in the last years of the study, which is confirmed by the analysis of the different panel patterns using -xtdescribe-. While some patterns' frequency is >1000, other patterns only occur once. To improve the data quality, I would like to drop all patterns that occur less than twenty times.
>
> I have not been able to accomplish this. Thus far, I can only re-generate the -xtdescribe- output again.
> xtpatternvar,gen(pattern)
> egen tag =tag(ID)
> tabulate pattern if tag, sort
>
> Any advice on how to drop low frequency patterns from panel data?
*
* 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/