02-16-2017 09:12 PM
I have a regression coefficient (y=1.11*x) of a regression model: KM % = 1.11*TEMR. In another independent data set say Set A, I have TEMR readings from the same instrument as well as KM% of 120 samples. Now if in the Set A, I first multiple TEMRx1.11 to get a variable say TEMR_modified and then like to test whether TEMR_modified would be any different from the KM% of the Set A?
What would be my options, please?
I first thought of treating TEMR_modified and Km% (both have N120) as two groups and run a two sample ttest, but don’t know if it would be valid (as I notice some occasional variation in both groups for respective readings).
Please, advise and if possible with a sas code, thank you all
02-16-2017 10:29 PM
You can check that your new data supports (does not disagree with) the hypothesis that TEMR = 1.11 KM with proc REG:
proc reg data=A; model TEMR = KM / noint; test KM = 1.11; run;
02-16-2017 11:26 PM
Thank you very much for your suggestion. I ran the code "test = km 1.11" the particular SAS Output is:
I guess the default null hypothesis for the test=1.11 would be that the "new regression model's coefficient (TEMR=KM)" is no different than 1.11?
So, what about the question I asked in my original post, how to test that "TEMR_modified is no different than KM%". Or the above test is sufficient? please. Thank you again
02-16-2017 11:58 PM
A 2 sample test might not have much power, depending on the range covered by km.
You could run a paired t-test of temr_modified and km. Or simply run proc univariate on diff = temr_modified - km.
If you have the original data that yielded the regression slope estimate of 1.11, you could also test that the original data and the new data yield the same slope.
02-17-2017 12:35 AM