Dropping group of variables if the group does not contain a certain value

Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#1

Dropping group of variables if the group does not contain a certain value

12 Mar 2021, 05:43

Dear all,

I am a stata beginner so this question might sound stupid. I have a dataset that list persons in a board of a public company for a given year. Moreover, I have specified whether someone is the CEO or not and if there has been a CEO succession event. The data is sorted by company and year. Now, I want to drop all the observations for a given company if there is no CEO succession event (for example, when the CEO remains in function in the whole period). If there is a CEO succession event, I want to keep all the observations (including the years where no succession is present). Looking at the screenshot below, I would like to drop all companies that look like that (where the CEO in the first year is also CEO in the last year). So, conceptually, all companies would be a separate group, then if this group (company) does not contain a ceo_change, the whole group gets dropped and if it does contain a ceo_change, the whole group stays.

I hope someone can help me with this, thanks in advance!
Tags: None

Ali Atia

Join Date: May 2020
Posts: 737

12 Mar 2021, 06:07

Code:

bysort company role (time): egen x = min(cond(role=="CEO",individual[_n]==individual[_N],0))
bysort company: egen y = max(x)
drop if y
drop x y

Comment

Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#3

12 Mar 2021, 07:15

Thanks for your reply, however I get the error 'individual ambiguous abbreviation'

code:
bysort company_name ceo_dummy (year): egen x = min(cond(ceo_dummy==1,individual[_n],0))
bysort company_name: egen y = max (x)
drop if y
drop x y

Instead of 'individualrole', I used 'ceo_dummy' as there are observations that include more text than just 'ceo' ('group ceo' for example). Therefore in the second part of the first line I changed the condition to ceo_dummy==1, indicating that someone is CEO. How could this be solved?

thanks in advance
Comment
Ali Atia

Join Date: May 2020

Posts: 737
#4

12 Mar 2021, 07:19

Change individual to individual_name.
Comment
Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#5

12 Mar 2021, 08:00

This gives me 'type mismatch' error. I changed individual_name to a variable called 'directorid' which is basically then same but numerical.

code:
bysort company_name ceo_dummy (year): egen x = min(cond(ceo_dummy==1,directorid[_n],0))
bysort company_name: egen y = max (x)
drop if y
drop x y

However, if I run all these lines, it drops all observations which contain a CEO, leaving me with a dataset without CEOs. What did I do wrong?

Thanks again for your help
Comment
Ali Atia

Join Date: May 2020

Posts: 737
#6

12 Mar 2021, 08:05

My error - I didn't realize your individual_name was a string. But in your amended code in #5, using the numeric variable, you omit an important part of the code. This should work:

Code:

bysort company_name ceo_dummy (year): egen x = min(cond(ceo_dummy==1,directorid[_n]==directorid[_N],0)) bysort company_name: egen y = max(x) drop if y drop x y

For future questions, please give a data example using -dataex-, which provides important information about your data and raises the likelihood that answers will work in the first instance.

Last edited by Ali Atia; 12 Mar 2021, 08:42.
Comment
Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#7

12 Mar 2021, 08:11

Thanks, the code:

bysort company_name ceo_dummy (year): egen x = min(cond(ceo_dummy==1,directorid[_n]==directorid[_N],0))
bysort company_name: egen y = max(x)
drop if y
drop x y

This code works, however, it drops 0 observations, which is weird. How could that be?
Comment

Ali Atia

Join Date: May 2020
Posts: 737

12 Mar 2021, 08:20

It should work, see this made-up example where in company #1, the ceo is always directorid #4, leading to it being dropped:

Code:

* Example generated by -dataex-. To install: ssc install dataex
clear
input float(company_name year directorid ceodummy)
1 2001 3 0
1 2002 4 1
1 2003 3 0
1 2004 4 1
1 2005 4 1
1 2006 3 0
1 2007 5 0
1 2008 4 1
1 2009 4 1
1 2010 1 0
2 2001 3 1
2 2002 1 0
2 2003 4 0
2 2004 3 1
2 2005 1 1
2 2006 3 1
2 2007 5 1
2 2008 5 0
2 2009 3 1
2 2010 1 1
3 2001 3 0
3 2002 3 1
3 2003 1 0
3 2004 4 1
3 2005 5 0
3 2006 5 0
3 2007 3 0
3 2008 2 1
3 2009 1 0
3 2010 5 1
end
bysort company_name ceodummy (year): egen x = min(cond(ceodummy==1,directorid[_n]==directorid[_N],0))
bysort company_name: egen y = max(x)
drop if y
drop x y

Code:

. list ,sepby(company_name) noobs

  +---------------------------------------+
  | compan~e   year   direct~d   ceodummy |
  |---------------------------------------|
  |        2   2002          1          0 |
  |        2   2003          4          0 |
  |        2   2008          5          0 |
  |        2   2001          3          1 |
  |        2   2004          3          1 |
  |        2   2005          1          1 |
  |        2   2006          3          1 |
  |        2   2007          5          1 |
  |        2   2009          3          1 |
  |        2   2010          1          1 |
  |---------------------------------------|
  |        3   2001          3          0 |
  |        3   2003          1          0 |
  |        3   2005          5          0 |
  |        3   2006          5          0 |
  |        3   2007          3          0 |
  |        3   2009          1          0 |
  |        3   2002          3          1 |
  |        3   2004          4          1 |
  |        3   2008          2          1 |
  |        3   2010          5          1 |
  +---------------------------------------+

If it's not working, that means your data looks different to how I think it does. Please provide a data example by typing -dataex company_name ceo_dummy year directorid- and pasting the output between code delimiters.

Comment

Coen VoitusvanHamme

Join Date: Mar 2021
Posts: 10

12 Mar 2021, 08:30

When I type that, this is my output:

Code:

* Example generated by -dataex-. To install: ssc install dataex
clear
input str128 company_name float ceo_dummy double(year directorid)
"1PM PLC"                                         0 2007  5899669191
"1PM PLC"                                         0 2007  5899749191
"1PM PLC"                                         0 2007  5899829191
"1PM PLC"                                         0 2007  5899909191
"1PM PLC"                                         0 2008  5899979191
"1PM PLC"                                         0 2008 63207812476
"1PM PLC"                                         0 2008  5899669191
"1PM PLC"                                         0 2008  5899749191
"1PM PLC"                                         0 2009  5899749191
"1PM PLC"                                         0 2009  5899979191
"1PM PLC"                                         0 2009  4855269108
"1PM PLC"                                         0 2009  5899669191
"1PM PLC"                                         0 2009 93753712245
"1PM PLC"                                         0 2010  5899749191
"1PM PLC"                                         0 2010 93753712245
"1PM PLC"                                         0 2010  5899669191
"1PM PLC"                                         0 2010  4855269108
"1PM PLC"                                         1 2010  5899979191
"1PM PLC"                                         0 2011  4855269108
"1PM PLC"                                         0 2011  5899749191
"1PM PLC"                                         0 2011  5899669191
"1PM PLC"                                         0 2011 93753712245
"1PM PLC"                                         1 2011  5899979191
"1PM PLC"                                         0 2012 93753712245
"1PM PLC"                                         0 2012  4855269108
"1PM PLC"                                         0 2012  5899669191
"1PM PLC"                                         0 2012  5899749191
"1PM PLC"                                         1 2012  5899979191
"1PM PLC"                                         0 2013  5899669191
"1PM PLC"                                         0 2013 93753712245
"1PM PLC"                                         0 2013  5899749191
"1PM PLC"                                         0 2013  4855269108
"1PM PLC"                                         1 2013  5899979191
"1PM PLC"                                         0 2014 93753712245
"1PM PLC"                                         0 2014  5899749191
"1PM PLC"                                         0 2014 14251427587
"1PM PLC"                                         0 2014  4855269108
"1PM PLC"                                         1 2014  5899979191
"1PM PLC"                                         0 2015  4855269108
"1PM PLC"                                         0 2015 93753712245
"1PM PLC"                                         0 2015 14251427587
"1PM PLC"                                         1 2015  5899979191
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006   693411741
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006  4780268417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2006  4780258417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007   693411741
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  4780268417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  4780328417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007 53473312886
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  3601346990
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2007  4780258417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2008 53473312886
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2008  4780268417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2008  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2008  4780258417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009 53473312886
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  8757636849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  8757666849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2010  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011 11369553543
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011 11374993565
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2011  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11374993565
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11428163671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2012  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11374993565
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2013  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014  5447713671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2014  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015  5447713671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2015  8757616849
end

Comment

Ali Atia

Join Date: May 2020
Posts: 737

#10

12 Mar 2021, 08:39

Using the code from #6 on your data example leads to company "1PM PLC" being dropped, because director #5899979191 is the CEO for the entire duration, but company "1SPATIAL PLC (Avisen PLC prior to 04/2012)" is retained because the CEO changes from 4780258417 to 8757616849. So I'm not sure why it's not working when you use it.

Code:

* Example generated by -dataex-. To install: ssc install dataex
clear
input str128 company_name float ceo_dummy double(year directorid)
"1PM PLC"                                         0 2007  5899669191
"1PM PLC"                                         0 2007  5899749191
"1PM PLC"                                         0 2007  5899829191
"1PM PLC"                                         0 2007  5899909191
"1PM PLC"                                         0 2008  5899979191
"1PM PLC"                                         0 2008 63207812476
"1PM PLC"                                         0 2008  5899669191
"1PM PLC"                                         0 2008  5899749191
"1PM PLC"                                         0 2009  5899749191
"1PM PLC"                                         0 2009  5899979191
"1PM PLC"                                         0 2009  4855269108
"1PM PLC"                                         0 2009  5899669191
"1PM PLC"                                         0 2009 93753712245
"1PM PLC"                                         0 2010  5899749191
"1PM PLC"                                         0 2010 93753712245
"1PM PLC"                                         0 2010  5899669191
"1PM PLC"                                         0 2010  4855269108
"1PM PLC"                                         1 2010  5899979191
"1PM PLC"                                         0 2011  4855269108
"1PM PLC"                                         0 2011  5899749191
"1PM PLC"                                         0 2011  5899669191
"1PM PLC"                                         0 2011 93753712245
"1PM PLC"                                         1 2011  5899979191
"1PM PLC"                                         0 2012 93753712245
"1PM PLC"                                         0 2012  4855269108
"1PM PLC"                                         0 2012  5899669191
"1PM PLC"                                         0 2012  5899749191
"1PM PLC"                                         1 2012  5899979191
"1PM PLC"                                         0 2013  5899669191
"1PM PLC"                                         0 2013 93753712245
"1PM PLC"                                         0 2013  5899749191
"1PM PLC"                                         0 2013  4855269108
"1PM PLC"                                         1 2013  5899979191
"1PM PLC"                                         0 2014 93753712245
"1PM PLC"                                         0 2014  5899749191
"1PM PLC"                                         0 2014 14251427587
"1PM PLC"                                         0 2014  4855269108
"1PM PLC"                                         1 2014  5899979191
"1PM PLC"                                         0 2015  4855269108
"1PM PLC"                                         0 2015 93753712245
"1PM PLC"                                         0 2015 14251427587
"1PM PLC"                                         1 2015  5899979191
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006   693411741
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2006  4780268417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2006  4780258417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007   693411741
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  4780268417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  4780328417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007 53473312886
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2007  3601346990
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2007  4780258417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2008 53473312886
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2008  4780268417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2008  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2008  4780258417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2009 53473312886
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  8757636849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010 30148711102
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  4780278417
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2010  8757666849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2010  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011 11369553543
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011 11374993565
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2011  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2011  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11374993565
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2012 11428163671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2012  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11374993565
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2013 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2013  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2014  5447713671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2014  8757616849
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015  5447713671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015  5524224997
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015 11320683456
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015 11428143671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      0 2015 11428173671
"1SPATIAL PLC (Avisen PLC prior to 04/2012)"      1 2015  8757616849
end
format %16.0g directorid
. list company directorid if ceo_dummy==1,sepby(company)

     +---------------------------------------------------------+
     |                               company_name   directorid |
     |---------------------------------------------------------|
 18. |                                    1PM PLC   5899979191 |
 23. |                                    1PM PLC   5899979191 |
 28. |                                    1PM PLC   5899979191 |
 33. |                                    1PM PLC   5899979191 |
 38. |                                    1PM PLC   5899979191 |
 42. |                                    1PM PLC   5899979191 |
     |---------------------------------------------------------|
 47. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   4780258417 |
 55. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   4780258417 |
 59. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   4780258417 |
 69. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 74. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 81. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 87. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 93. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 99. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
     +---------------------------------------------------------+

Code:

bysort company_name ceo_dummy (year): egen x = min(cond(ceo_dummy==1,directorid[_n]==directorid[_N],0))
bysort company_name: egen y = max(x)
drop if y
drop x y

Code:

. list company directorid if ceo_dummy==1,sepby(company)

     +---------------------------------------------------------+
     |                               company_name   directorid |
     |---------------------------------------------------------|
 49. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   4780258417 |
 50. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   4780258417 |
 51. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   4780258417 |
 52. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 53. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 54. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 55. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 56. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
 57. | 1SPATIAL PLC (Avisen PLC prior to 04/2012)   8757616849 |
     +---------------------------------------------------------+

Comment

Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#11

12 Mar 2021, 08:46

That's weird, I have again copy pasted the code that you wrote and it still does not work. Furthermore, when I look at variable x and y, they all give the value 0, which explains why nothing is dropped I think. Maybe that's where the mistake lies?
Comment

Ali Atia

Join Date: May 2020
Posts: 737

#12

12 Mar 2021, 09:43

Here's an alternative, though I'm stumped as to why the code from #6 works on the data example but not on the actual data:

Code:

bysort company_name ceo_dummy: egen maxceo=max(directorid)
bysort company_name ceo_dummy: egen minceo=min(directorid)
bysort company_name: egen max = max(cond(ceo_dummy==1,maxceo==minceo,0))
drop if max
drop max* min

Comment

Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#13

12 Mar 2021, 09:57

It seems to work now, thank you for your help!!
Comment
Coen VoitusvanHamme

Join Date: Mar 2021

Posts: 10
#14

19 Mar 2021, 03:21

After some review, I have found another issue. The code works perfectly, however, there are some companies in my dataset that do not have a CEO at all. Do you perhaps know how I can modify the code so that it also drops the companies for which the ceo_dummy is always 0?
Comment
Ali Atia

Join Date: May 2020

Posts: 737
#15

19 Mar 2021, 04:53

Code:

bysort company_name: egen maxdummy=max(ceo_dummy) drop if maxdummy==0
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Comment

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