Create new variable from de comparation of the values of two variables

[Rob Arrow]

Hi everyone,

I am student, recently using stata, having touble with the creation of variables Here is a simplified version of my data:

row	sales_2022	sales_2023
1	39011	39011
2	51805	0
3	11921	11921
4	0	77823
5	14283	14283

I am looking for a way in which Stata could do the followings:

1.Create a new variable (for example "sales_comparation")
2. Then replace the variable "sales_comparation" with the value common values between sales_2022 and sales_2023
3. Replace with missing the variable "sales_comparation" when values are not the samen sales_2022 and sales_2023

The result should be this

row	sales_2022	sales_2023	sales_comparation
1	39011	39011	39011
2	51805	0
3	11921	11921	11921
4	0	77823
5	14283	14283	14283

thanks for any help!
regards

Rob

[Clyde Schechter]

gen wanted = sales_2022 if sales_2022 == sales_2023

[Daniel Schaefer]

Seems like you want something like this:

gen sales_comparison = sales_2022 if sales_2022 == sales_2023

Although there are a few things to note. First, if you want to do this for multiple years, then you should transform this from the wide format to the long format first. In fact, you probably want to do that regardless. See:

help reshape

And, just as a quick note, I don't know exactly what you want to do here, but it seems like it should be way more straight forward and useful to take the difference (if they are the same the difference is zero) or create an indicator (1 if sales were the same, otherwise 0) to get a variable that will be useful later in the analysis.

Edit: crossed with #2.

[Rob Arrow]

Thanks to the both of you Clyde and Daniel, very helpful information!!

Regards