Dear Listers,
Any help with the below problem would be very much appreciated:
I have a wide dataset with the following variables:
ID, Specimen1, Spec2......Spec11, StartDate, EndDate
ID contains an identifier as you might already have guessed
Spec1 to Spec11 contain collection dates (in ascending order) for the
first, 2nd, 3rd etc. specimen. Spec1 has a complete set of
observations, Spec2 is only non-missing if there was more than one
Spec for that person etc. Spec Dates for the same specimen rank vary
between different observations.
