Selecting the last year attended

PDevi — Tue, 11 Aug 2020 20:33:37 GMT

Hi all,

I have data as below, with employees attending conferences over a number of years.

Data:

id Year

1 2017

1 2018

2 2017

2 2018

2 2019

2 2020

3 2019

I have to find the most recent year that the participant attended previously for each year. So, what I need is this:

Result needed:

id Year Previously_attended

1 2017

1 2018 2017

2 2017

2 2018 2017

2 2019 2018

2 2020 2019

3 2019

I can't figure out how to do this and would appreciate help. Thanks in advance for your time and patience.

Re: Selecting the last year attended

Reeza — Tue, 11 Aug 2020 20:39:00 GMT

LAG function.

data want;
set have;
by ID;
previously_attended = lag(year);
if first.id then call missing(previously_attended);
run;