topic Testing Slope=ONE in Statistical Procedures

Testing Slope=ONE

AlBest — Sat, 07 Jan 2017 15:02:17 GMT

In an ANCOVA-like model (using GLM or MIXED or whatever) how do I test whether a Slope=ONE.

(not zero, 1) ... testing whether the estimated slope = 1.

Proc GLM;

Class Group;

Model Y= Group X;

... something like: TEST X=1;

=== I know I could look at the CI for the parameter estimates and see if it contains 1; I want a p-value.

???

Re: Testing Slope=ONE

sld — Sat, 07 Jan 2017 18:09:45 GMT

The TESTVALUE= option on the ESTIMATE or LSMESTIMATE statement will do that. See

https://support.sas.com/resources/papers/proceedings11/351-2011.pdf

for an example. The TESTVALUE= option is not available for all procedures--for example, it is not available for GLIMMIX--but in those cases you can use the STORE statement and then use the PLM procedure to obtain the ESTIMATE or LSMESTIMATE statement with TESTVALUE option.

Re: Testing Slope=ONE

AlBest — Sat, 07 Jan 2017 18:45:24 GMT

Sorry, but the TESTVALUE= option is not available in GLM. In MIXED, the option is available in the LSMEstimate statement, but it only allows CLASS values as an effect. I need to test whether the slope of a continuous covariate is 1.

But, I appreciate the thought. I learned something.

Re: Testing Slope=ONE

sld — Sat, 07 Jan 2017 18:59:56 GMT

True, the TESTVALUE option is not available for the ESTIMATE statement in many SAS procedures (including GLM and MIXED, as well as GLIMMIX), which I noted in my response. (For testing a specific slope value, you would use ESTIMATE rather than LSMESTIMATE.)

But, as I also noted, you can use the STORE statement in GLM (or MIXED or GLIMMIX), and then the PLM procedure with the ESTIMATE statement and the TESTVALUE option. See

https://support.sas.com/resources/papers/proceedings10/258-2010.pdf

for more information about the PLM procedure; SAS documentation provides even more details. A chance to learn even more 🙂

Re: Testing Slope=ONE

AlBest — Sat, 07 Jan 2017 19:02:56 GMT

Ah. I spoke too soon.

Outputing a STORE in MIXED and then using the ESTIMATE statement in PLM works!

cool

Re: Testing Slope=ONE

sld — Sat, 07 Jan 2017 19:04:26 GMT

It is cool! I'm glad it worked for you.

Re: Testing Slope=ONE

Reeza — Sun, 08 Jan 2017 04:31:13 GMT

@AlBest Please mark answer as correct