Hello, I am trying to get some frequency numbers for two patient populations:   Pop 1 : Patients who have an initial  behavior code of 0 followed by behavior code 1 based on year of diagnosis (yod). Pop 2: Patients who have an initial behavior code of 0 followed by behavior code 1 based on diagnosis (yod).   Some patients have up to 6 diagnosis but I am only interested in the first 2 as explained above based on the yod.   How would you code this given I have multiple diagnosis (behavior_code) and different yod to obtain the n’s for each population?   Here is an example of some of the variables I am working with:   patient_id age yod behavior_code det_sequence_no 1 55-59 years 2011 0 1 1 60-64 years 2015 1 2 2 55-59 years 2001 0 1 2 55-59 years 2002 1 2 3 70-74 years 2002 0 1 3 75-79 years 2007 1 2 4 45-49 years 2003 0 1 4 50-54 years 2008 0 2 4 50-54 years 2009 1 3 4 60-64 years 2018 1 4   Thank you so much in advance! ... View more