st: time-series data identified by three variables

[yannan shen <yannan2010@gmail.com>]

Dear statalist,
I am working some panel data of hospital visits and I want to learn
the severity of various disease.
The variables I have in the dataset are: patient_id, illness_id,
date_of_visit, severity
each observation contains: patient_id, illness_id, date_of_visit, severity.

For each patient (identified by patient_id), I want to know how many
of times he has visited for the same illness （illness_id ).
I use the duple command to to label the observation of patients who
have visited hospital more than once.

> duplicates tag  patient_id illness_id , generate(duple)

However, duple does not give information for any time series
information. If a patient has 5 visiting records, I want to be able to
know which is the 0th repeat, 1st repeat, 2nd repeat, 3rd repeat, and
4th repeat...I have a vague feeling that I can order those variables
via date_of_visit but I am still not sure how exactly that can be
done.

Furthermore, I want to create two new variables: one variable equals
to the average severity of each disease (disease_id) being treated on
the same date_of_visit. The other variable equals the highest severity
of a certain disease being treated on that day. (Ideally, I want to
create additional variables for each observation)

I have used “bysort” in the past but since now the type is a
combination of illness_id and date_of_visit， I am a little confused.
I appreciate your help and suggestions.

Best,

Y.S

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