Bookmark and Share

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: RE: what command to keep firms-years with multiple occurrence of only one type of events


From   Roberto Ferrer <[email protected]>
To   Stata Help <[email protected]>
Subject   Re: st: RE: what command to keep firms-years with multiple occurrence of only one type of events
Date   Fri, 27 Sep 2013 16:39:11 +0100

Seems Robert beat me to that one.

Bests,
Roberto

On Fri, Sep 27, 2013 at 4:37 PM, Roberto Ferrer <[email protected]> wrote:
> If I understand correctly, the following should work. Just -sort-,
> compare first event with last event and keep the event that interests
> you.
>
> *-------------------------- begin example --------------------------------------
> clear
> input str2 firm year event
> A        1994       2
> A        1994       3
> A        1994       3
> A        1995       1
> A         1995      3
> A         1996       2
> A         1996       4
> A         1996       3
> A          1997       3
> A           1997      3
> A           1998       1
> A            1998       1
> B         1995      3
> B         1996       2
> B         1996       4
> B         1996       3
> end
>
> * what you want
> sort firm year event
> by firm year: keep if event[1] == event[_N] & event == 3
>
> *----------------------- end example -------------------------------------------
>
> On Fri, Sep 27, 2013 at 2:39 PM, Robert Picard <[email protected]> wrote:
>> Another way:
>>
>> bys Firm Year (Event): keep if (Event[1]==Event[_N]) & Event==3
>>
>> Robert
>>
>> On Fri, Sep 27, 2013 at 9:29 AM, Joe Canner <[email protected]> wrote:
>>> Nahla.
>>>
>>> If your Event variable is numeric, this should work:
>>>
>>> . bys Firm Year: egen mn=mean(Event)
>>> . bys Firm Year: egen sd=sd(Event)
>>> . keep if mn==3 & sd==0
>>>
>>> This is, admittedly, a little unconventional, but should be pretty efficient.
>>>
>>> Regards,
>>> Joe Canner
>>> Johns Hopkins University School of Medicine
>>>
>>> -----Original Message-----
>>> From: [email protected] [mailto:[email protected]] On Behalf Of Nahla Betelmal
>>> Sent: Friday, September 27, 2013 4:43 AM
>>> To: [email protected]
>>> Subject: st: what command to keep firms-years with multiple occurrence of only one type of events
>>>
>>> Dear Statalist members,
>>>
>>> It would be great if you can let me know what command I can use to keep firms-years with multiple occurrence of only one type of events in my data.
>>>
>>> I have firms-years-events data set. A firm can have multiple entries for the same year if it undertakes certain corporate events . I coded the events as 1,2,3, 4. For example the data looks like this
>>>
>>>
>>> Firm   Year    Event
>>> A        1994       2
>>> A        1994       3
>>> A        1994       3
>>> A        1995       1
>>> A         1995      3
>>> A         1996       2
>>> A         1996       4
>>> A         1996       3
>>> A          1997       3
>>> A           1997      3
>>> A           1998       1
>>> A            1998       1
>>> B
>>> ..
>>>
>>>
>>> I am only interested in studying firm-years where  only event 3 was undertaken (i.e. keep both entries for year 1997 only). In other words, I want to drop firm years where there are a mix of events shown as multiple entries/observations ( years 1994, 1995, 1996) and multiple unique occurrence of event other than 3 (year 1998).
>>>
>>> I understand that I can do it on two stages, first drop  firm-years with mix events, then second stage drop years with unique events other than 3.
>>>
>>> the problem that I  don't know what command should I use to do the first stage ( drop firms-years with multiple entries of multiple events).
>>>
>>> Thank you in advance, I highly appreciate your kind help
>>>
>>> Nahla Betelmal
>>> *
>>> *   For searches and help try:
>>> *   http://www.stata.com/help.cgi?search
>>> *   http://www.stata.com/support/faqs/resources/statalist-faq/
>>> *   http://www.ats.ucla.edu/stat/stata/
>>>
>>> *
>>> *   For searches and help try:
>>> *   http://www.stata.com/help.cgi?search
>>> *   http://www.stata.com/support/faqs/resources/statalist-faq/
>>> *   http://www.ats.ucla.edu/stat/stata/
>>
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/faqs/resources/statalist-faq/
>> *   http://www.ats.ucla.edu/stat/stata/

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


© Copyright 1996–2018 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   Site index