topic Re: ODDS ratio- with reference level in SAS Programming

ODDS ratio- with reference level

ahhh — Thu, 13 Apr 2017 22:33:18 GMT

Hi, I need to calculate odds ratios, while keeping this group of time variable as referance -(6 months to less than 12 months).

I am new to this, please check the below code and I want to make sure I am doing this correctly.

I appreciate your timely help!

Thank you.

proc format;
value timef 1='6 months to less than 12 months '
2='12 months to less than 24 months '
3='24 months to less than 36 months '
4='36 months and above';

value $oldf '0'='Young'
'1'='Old'
;
run;

data one;
input old $1. time;
datalines;
1 1
0 2
1 3
1 2
0 1
1 3
0 2
1 3
0 4
1 4
0 3
1 4
;
run;

data two;
set one;
format time timef.;
run;

ods graphics on;
proc logistic data=two plots(only)=(effect (clband) oddsratio (type=horizontalstat));
class time(param=ref ref="6 months to less than 12 months");
model old (event="1") = time/clodds=pl;
run;
ods graphics off;

Re: ODDS ratio- with reference level

CiCi — Fri, 14 Apr 2017 01:06:18 GMT

The way you put referece level looks correct to me. I tested your code. You can find a table "Class Level Information" from the output (see below). The "0-0-0" in "Design Variables" represents the reference group, which is what you specified.

Be careful about your formats. Better to remove those blanks from format. Sometime, this can cause unexpected problem and can be hard to debug.

Proc Format;

Value timef

1='6 months to less than 12 months '
2='12 months to less than 24 months '
3='24 months to less than 36 months '
4='36 months and above'

;

Value $oldf

'0'='Young'
'1'='Old'
;

run;

Re: ODDS ratio- with reference level

CiCi — Fri, 14 Apr 2017 01:07:31 GMT

BTW, I cannot attached the table due to HTML error....Try to find the table labelled as "Class Level Information".

Re: ODDS ratio- with reference level

Ksharp — Fri, 14 Apr 2017 14:03:10 GMT

use ODDSRATIO statement or

use

model old (event="1") = time/clodds=pl EXP ;