Tips:
1. Work with native Stata date variables. So you will
want to create
. gen start_date = mdy(startm,startd,starty)
be sure "starty" is four digits (eg, 2008, not 08).
Similarly,
. gen survey_date = mdy(surveym,surveyd,surveyy)
and then format them as dates for convenience
. format start_date survey_date %d
2. Then it is easy to convert these to elapsed months:
. gen start_month=mofd(start_date)
. gen survey_month=mofd(survey_date)
will create two variables, each giving the number of months
elapsed since 1/1/1960. After this, it's a small matter
to get the difference in months:
. gen treatment_months = survey_month-start_month
hope this helps,
Jeph
Ziad El-Khatib wrote:
Hi!
I entered dates of patients starting on treatment and date of their
interview under different variables:
startd (for day)
startm (for month)
starty (for year)
surveyd (for day)
surveym (month)
surveyy (year)
Now i want to calculate number of months patients have been on treatment.
I am finding problems in creating
start=startd+startm+starty
survey=surveyd+surveym+surveyy
period=survey-start
Any tips?
Thank you and best regards
ziad
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