Generate treatment variables for panel data analysis

[Felix Tietge]

Dear community,

I am working on a panel data analysis, where I have to generate a treatment variable. The panel data only covers two waves of household data, one from 2019 and one from 2022.
The treatment variable should indicate that at least one household member was contracted with Covid-19. The problem is that my treatment dummy only indicates the value of one for the year 2022 but not for the same subject in 2019.

The commands I used so far are:

gen time = 1 if year==2022,
replace time = 0 if year==2019,

xtset QID time

gen treated= 1 if cov_infected_cov!=0,
replace treated = 0 if cov_infected_cov==0


I would be very thankful for any advice to fix this problem.

Best regards!

[Carlo Lazzaro]

Felix:
welcome to this forum.
Some comments about your query:
1) why creating a time variable when you seemingly have one already (year)?
2) as per your first chunck of code I'd say you're after a difference in difference study (pre/post; treatment/control).

[Felix Tietge]

Hello Mr. Lazzaro,
thank you for the response, I am a beginner in Stata.

I generated the time variable because I was told to do so in order to have a time dummy.

Yes, I want to apply the difference in difference and the problem is that the treatment variable is not showing the value of one for the treated subjectives for the year 2019.

I am looking forward to your response.

Kind regrads,
Felix

[Carlo Lazzaro]

Felix:
1) the issue seems to be that in 2019 the pandemic did not outbreak yet: hence, the value of the variable -covid_infected- should be zero regardless of the group.
2) I'm fine with the creation of a -timevar-. However, if -year- variable is in numeric format already, you can simply code -i.year- to create a predcitor.

[Felix Tietge]

Dear Mr. Lazzaro,

thank you for your help.
I will work further with your advice.

Kind regards,
Felix