topic Re: recoding variable around on median of variable in SAS Programming

recoding variable around on median of variable

Tpham — Mon, 12 May 2014 19:06:00 GMT

So I have a variable called cumlative dosage. I want to code a patient to see if they are above or the below the median dosage.

So when I run:

proc means data=temp n min max median;

var avcumdos_6wper;

run;

This is the following output

N Minimum Maximum Median

ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ

184 1.1695906 10.4000000 4.0354701

ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ

So I want to calculate a flag variable around that mean. where flag=. if avcumdos_6wper=., flag=1 if avcumdos_6wper <= median or flag=2 if avcumdos_6wper> median.

So I figure I can do this via sql, but i can't seem to get it to work. It just copies the variable. This is my code thus far:

proc sql;

create table temp1 as

select patientid, visit, avcumdos_6wper, median(avcumdos_6wper) as mv,

case when avcumdos_6wper = . then .

when avcumdos_6wper <= calculated mv then 1

when avcumdos_6wper > calculated mv then 2

else 999 end as flag

from temp;

Can someone tell me what I am doing wrong?

Re: recoding variable around on median of variable

Reeza — Mon, 12 May 2014 19:19:55 GMT

Are you on SAS 9.4? Before SAS 9.4 proc SQL cannot calculate the median.

Re: recoding variable around on median of variable

ballardw — Mon, 12 May 2014 21:00:50 GMT

If median works it is only working on one record at a time with your syntax. My current SAS does not have the median function available in SQL but you may be looking for something like:

proc sql;

create table temp1 as

select patientid, visit, avcumdos_6wper, b.mv,

case when avcumdos_6wper = . then .

when avcumdos_6wper <= b.mv then 1

when avcumdos_6wper > b.mv then 2

else 999 end as flag

from temp join (select median(avcumdos_6wper) as mv from temp) as b;

quit;