Problems removing certain observations of a variable

[Qi vd Kolk]

Hi all,

I have a panel dataset with CEO data for the years 2016-2020, but I want to remove the boards that do not provide CEO data for 2016, 2017, 2018, 2019, 2020.
For instance, a board only provides CEO data for years 2016 and 2017 and this board I want to remove from the dataset.
I used the following code:

isid BoardID AnnualReportDate year
assert inrange(year, 2016, 2020)
bys year : keep if _N== 5

The result is that all of the observations in the data set are deleted.I tried different combinations for instance I also used isid RoleName AnnualReportDate DirectorID year but every time all observations are deleted.
Note: I added the variable year manually as the dataset only had the variable AnnualReportDate.

Which code do I need that only removes the boards that do not have CEO data for years 2016-2020?

Below a sample of my dataset:
I'm using Stata 17 on a macOS Catalina version 10.15.7

* Example generated by -dataex-. For more info, type help dataex
clear
input str12 ISIN long BoardID str41 RoleName int(AnnualReportDate year)
"US90214J1016" 2057807 "CEO"                    20789 2016
"US90214J1016" 2057807 "CEO"                    21154 2017
"US90214J1016" 2057807 "CEO"                    21519 2018
"US90214J1016" 2057807 "CEO"                    21884 2019
"US90214J1016" 2057807 "CEO"                    22250 2020
"US88554D2053"     276 "President/CEO"          20789 2016
"US88554D2053"     276 "President/CEO"          21154 2017
"US88554D2053"     276 "President/CEO"          21519 2018
"US88554D2053"     276 "President/CEO"          21884 2019
"US88554D2053"     276 "President/CEO"          22250 2020
"US88579Y1010"   20777 "Chairman/President/CEO" 20789 2016
"US88579Y1010"   20777 "Chairman/President/CEO" 21154 2017
"US88579Y1010"   20777 "CEO"                    21519 2018
"US88579Y1010"   20777 "Chairman/President/CEO" 21884 2019
"US88579Y1010"   20777 "Chairman/President/CEO" 22250 2020
"US00287Y1091" 1921326 "Chairman/CEO"           20789 2016
"US00287Y1091" 1921326 "Chairman/CEO"           21154 2017
"US00287Y1091" 1921326 "Chairman/CEO"           21519 2018
"US00287Y1091" 1921326 "Chairman/CEO"           21884 2019
"US00287Y1091" 1921326 "Chairman/CEO"           22250 2020
"US00430H1023"     569 "President/CEO"          20789 2016
"US00430H1023"     569 "President/CEO"          21154 2017
"US00430H1023"     569 "President/CEO"          21519 2018
"US00430H1023"     569 "President/CEO"          21884 2019
"US00430H1023"     569 "President/CEO"          22250 2020
"US00081T1088"  665743 "Chairman/President/CEO" 20789 2016
"US00081T1088"  665743 "Chairman/President/CEO" 21154 2017
"US00081T1088"  665743 "Chairman/President/CEO" 21519 2018
"US00081T1088"  665743 "Chairman/President/CEO" 21884 2019
"US00081T1088"  665743 "Chairman/President/CEO" 22250 2020
"US00461U1051" 2351879 "President/CEO"          20789 2016
"US00461U1051" 2351879 "President/CEO"          21154 2017
"US00461U1051" 2351879 "President/CEO"          21519 2018
"US00461U1051" 2351879 "President/CEO"          21884 2019
"US00461U1051" 2351879 "President/CEO"          22250 2020
"US00484M6012"  247122 "President/CEO"          20789 2016
"US00484M6012"  247122 "President/CEO"          21154 2017
"US00484M6012"  247122 "President/CEO"          21519 2018
"US00484M6012"  247122 "President/CEO"          21884 2019
"US00484M6012"  247122 "President/CEO"          22250 2020
"US00507V1098"     725 "President/CEO"          20789 2016
"US00507V1098"     725 "CEO"                    21154 2017
"US00507V1098"     725 "CEO"                    21519 2018
"US00507V1098"     725 "CEO"                    21884 2019
"US00507V1098"     725 "CEO"                    22250 2020
"US00508Y1029"     733 "Chairman/President/CEO" 20667 2016
"US00508Y1029"     733 "Chairman/President/CEO" 21032 2017
"US00508Y1029"     733 "Chairman/President/CEO" 21397 2018
"US00508Y1029"     733 "Chairman/President/CEO" 21762 2019
"US00508Y1029"     733 "President/CEO"          22128 2020
"US00738A1060"     829 "Chairman/CEO"           20789 2016
"US00738A1060"     829 "Chairman/CEO"           21154 2017
"US00738A1060"     829 "Chairman/CEO"           21519 2018
"US00738A1060"     829 "Chairman/CEO"           21884 2019
"US00738A1060"     829 "Chairman/CEO"           22250 2020
"US00773T1016" 2536336 "President/CEO"          20789 2016
"US00773T1016" 2536336 "President/CEO"          21154 2017
"US00773T1016" 2536336 "President/CEO"          21519 2018
"US00773T1016" 2536336 "President/CEO"          21884 2019
"US00773T1016" 2536336 "President/CEO"          22250 2020
"US00771V1089" 2000812 "Chairman/CEO"           20789 2016
"US00771V1089" 2000812 "Chairman/CEO"           21154 2017
"US00771V1089" 2000812 "Chairman/CEO"           21519 2018
"US00771V1089" 2000812 "Chairman/CEO"           21884 2019
"US00771V1089" 2000812 "Chairman/CEO"           22250 2020
"US00847X1046" 1967527 "President/CEO"          20789 2016
"US00847X1046" 1967527 "President/CEO"          21154 2017
"US00847X1046" 1967527 "President/CEO"          21519 2018
"US00847X1046" 1967527 "CEO"                    21884 2019
"US00847X1046" 1967527 "CEO"                    22250 2020
"US00972D1054" 2055831 "President/CEO"          20789 2016
"US00972D1054" 2055831 "President/CEO"          21154 2017
"US00972D1054" 2055831 "President/CEO"          21519 2018
"US00972D1054" 2055831 "President/CEO"          21884 2019
"US00972D1054" 2055831 "President/CEO"          22250 2020
"US98973P1012"  735327 "CEO"                    21519 2018
"US98973P1012"  735327 "CEO"                    21884 2019
"US98973P1012"  735327 "CEO"                    22250 2020
"US01973R1014" 1806302 "Chairman/CEO"           20789 2016
"US01973R1014" 1806302 "Chairman/CEO"           21154 2017
"US01973R1014" 1806302 "President/CEO"          21519 2018
"US01973R1014" 1806302 "President/CEO"          21884 2019
"US01973R1014" 1806302 "President/CEO"          22250 2020
"US01988P1084"    1532 "CEO"                    20789 2016
"US01988P1084"    1532 "CEO"                    21154 2017
"US01988P1084"    1532 "CEO"                    21519 2018
"US01988P1084"    1532 "CEO"                    21884 2019
"US01988P1084"    1532 "CEO"                    22250 2020
"US02043Q1076"  117536 "CEO"                    20789 2016
"US02043Q1076"  117536 "CEO"                    21154 2017
"US02043Q1076"  117536 "CEO"                    21519 2018
"US02043Q1076"  117536 "CEO"                    21884 2019
"US02043Q1076"  117536 "CEO"                    22250 2020
"US02156B1035" 2638015 "Chairman/CEO"           21154 2017
"US02156B1035" 2638015 "Chairman/CEO"           21519 2018
"US02156B1035" 2638015 "Chairman/CEO"           21884 2019
"US02156B1035" 2638015 "CEO"                    22250 2020
"US02208R1068"  930959 "Chairman/President/CEO" 20789 2016
"US02208R1068"  930959 "Chairman/President/CEO" 21154 2017
"US02208R1068"  930959 "Chairman/President/CEO" 21519 2018
end
format %tddd-Mon-YY AnnualReportDate

Thanks in advance!

[Andrew Musau]

Clearly, the restriction is at the firm (board) level [and not year], so you need

isid BoardID AnnualReportDate year
assert inrange(year, 2016, 2020)
bys BoardID: keep if _N== 5

[Carlo Lazzaro]

Qi:
similar to Andrew's helpful reply, but a bit of -table- flavour:

. tab year

       year |      Freq.     Percent        Cum.
------------+-----------------------------------
       2016 |         19       19.00       19.00
       2017 |         20       20.00       39.00
       2018 |         21       21.00       60.00
       2019 |         20       20.00       80.00
       2020 |         20       20.00      100.00
------------+-----------------------------------
      Total |        100      100.00

. bysort BoardID (year): drop if _N<5
(10 observations deleted)

. tab year

       year |      Freq.     Percent        Cum.
------------+-----------------------------------
       2016 |         18       20.00       20.00
       2017 |         18       20.00       40.00
       2018 |         18       20.00       60.00
       2019 |         18       20.00       80.00
       2020 |         18       20.00      100.00
------------+-----------------------------------
      Total |         90      100.00

.