LOS summing

[Todd Greene]

Greetings Statalist users. I need to sum "days8dtotal" per patient across unique "stay". Based on descriptive merged data, many patients will have many rows of data with identical data. The following is a cut of these 2 variables for one patient. Stay = 1 has 21 rows of data and Stay=2 only 1 row. I really just need an effective way to sum total days for each patient across stays. So, for this particular patient, 2 distinct stays within 8D for a total of 13 days in 8D. Thanks.



days8dtotal stay

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

8 1

5 2

[Clyde Schechter]

Well, the simplest way would be to remove the duplicate observations and then calculate your sum. But on the assumption that there is some good reason you need to retain the duplicate obesrvations, you can also do it like this:

by patient_id stay (days8dtotal), sort: assert days8dtotal[1] == days8dtotal[_N]
egen flag = tag(patient_id stay)
by patient_id (stay), sort: egen wanted = total(cond(flag, days8dtotal, .))

Replace patient_id by the actual name of whatever variable(s) identify patients in your data.


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