How to derive WOCF?

[dpa]

Hi I want to use WOCF for my dataset but How can you do that.  so I have two dataset code which one i have and what i want. please help me I tried Lag but didn't succeed.

data have;
input id $ visitnum aval ;
datalines;
1 1 0
1 2 3
1 3 3
1 4 4
1 5 3
1 6 3
1 7 3
1 8 4
1 9 4
;
run;

data want;
input id $ visitnum aval dtype ;
datalines;
1 1 0
1 2 3
1 3 3
1 4 4
1 5 4 WOCF
1 6 4 WOCF
1 7 4 WOCF
1 8 4
1 9 4
;

run;

[Reeza]

What is WOCF?
Worst observation carried forward?

[dpa]

yes

[Reeza]

Lag or DIF or RETAIN are options. Show the code you tried with Lag please.

[dpa]

with Lag function I only manqged to change next one but i don't know how to do that with other two .

[Kurt_Bremser · Accepted solution]

retain _aval;
if first.id then _aval = aval;
if aval lt _aval
then do;
  aval = _aval;
  dtype = 'WOCF';
end;
else _aval = aval;
drop _aval;