Programming the statistical procedures from SAS

odds ratio interpretation

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New Contributor
Posts: 2

odds ratio interpretation

A case-control study was conducted to assess the association between exposure to tobacco smoke (TS) and lung cancer. 300 lifelong nonsmoking lung cancer cases and 1,288 nonsmoking controls were interviewed about exposure to ETS. Let cancer=I(lung cancer), ts= I(exposed to TS), gender=I(female). A logistic regression model was fit using the following SAS code

 

proc logistic data=cancer  descending;

model cancer/count = ets gender ets*gender; run;

 

Here is part of the SAS    output.

Analysis of Maximum  Likelihood  Estimates

 

 

Parameter

 

DF

 

Estimate

Standard

Error

Wald Chi-Square

 

Pr

 

> ChiSq

Intercept

1

-1.8946

0.2398

62.4070

 

<.0001

ts

1

-0.8134

0.2926

7.7308

 

0.0054

gender

1

1.0512

0.2653

15.6951

 

<.0001

ts*gender

1

0.8450

0.3320

6.4790

 

0.0109

 

How do you estimate odds lung cancer for males with ETS exposure?

Grand Advisor
Posts: 16,850

Re: odds ratio interpretation

Look at using the ODDSRATIO statement to determine the odds ratio for a variable in the interaction term.

 

Note that if your variables are categorical there should be a CLASS statement in your PROC and you should also define the coding type (GLM, REF, etc)

 

 

PS I'm going to move this to the Statistical Procedures forum.

 

New Contributor
Posts: 2

Re: odds ratio interpretation

Thank you.This is one of questions in a problem set_neither complete output or data is given to rerun the codes.How can I determine the odds ratio of lung cancer in males with TS exposure using the information on the estimates in the table?
Grand Advisor
Posts: 16,850

Re: odds ratio interpretation

Ok...then that's a stats question, not a  programming question. 

 

I have no idea how males/females or treatment are coded but you can calculate the probability by hand if you write the model for males with treatment out and then calculate the estimate. The exponent of that value would be the odds ratio.

 

 

 

 

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