Count number of periods with first firm after finding a job.

[Henry Strawforrd]

I want to count the number of periods within the next X periods, that a person stayed with the first firm after finding a job. The difficulty I am having is that I want to skip gaps, and also there is two types of jobs and I have to ignore one. So the standard spell counting did not work for me.

Here is an MWE with the important cases. I have panel data of individuals (id) periods (t) who either have a job (job=1) or not (job=0). There is two types of jobs, and I want to ignore the type for whom job_type=0. Employers are identified by empl_id.

input id t job job_type empl_id
1 1 0 . .
1 2 1 1 1
1 3 1 1 1
1 4 1 1 2
1 5 1 1 2
2 1 0 . .
2 2 0 . .
2 3 1 0 2
2 4 1 1 3
2 5 1 1 3
2 6 1 1 3
3 1 0 . .
3 2 1 1 4
3 3 1 1 4
3 4 0 . .
3 5 1 1 4
3 6 1 1 4
end

Cases, and say we count 6 periods:

• Person with id 1 got a job in period 2, this is the right type so the first firm is firm_id = 1. They stayed for two period with this firm and then switched firm. Therefore, the resulting number of periods as first firm should be 2.
• Person with id 2 got a job in period 3, however this job was type=0 so we don't count it. But in period 4 the job was right, and afterwards the person stay with that firm for three periods. So the resulting counter should be 3 here
• Person got a correct job in period 2. We count two periods with that, and then comes the difficulty. There is a break in between but then the person continued with that firm. I need the variable to ignore this break and give a total of 4 periods.

[Clyde Schechter]

//  FIRST IDENTIFY THE APPROPRIATE START TIME AND ASSOCIATED EMPL_ID
by id (t), sort: egen ref_time = min(cond(job_type == 1, t, .))
by id (t): egen ref_empl_id = max(cond(t == ref_time, empl_id, .))

//  COUNT UP TENURE WITH THAT EMPL_ID IN JOB TYPE 1 FROM THAT TIME ONWARD
by id (t): egen wanted = total(t >= ref_time & job_type == 1 & empl_id == ref_empl_id)

Added: You did not say what you want to do if an ID starts a type 1 job with an empl_id and subsequently continues with that same empl_id but job_type changes to 0 (with or without changing back to 1 after that). The code above assumes you do not want to count the times when job_type is 0 in this situation.

I also assume that if, after starting a type 1 job with an empl_id, ID switches temporarily to another empl_id (with job_type 0 or 1) and then switches back to the first empl_id in a type 1 job, you want to count all of the time spent with empl_id in a type 1 job, notwithstanding the interlude with another employer.

[Henry Strawforrd]

Both assumptions are correct, and wonderful code thank you!