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help using TEST in MIANALYZE

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help using TEST in MIANALYZE

I am using PROC MIANALYZE after PROC MIXED. 

 

In trying to run a post-estimation test comparing two linear combinations of variables, using the TEST statement in PROC MIANALYZE, I am having trouble with what I am trying to do, so I am hoping someone can tell me if it is possible.

 

This is an example of what I'm trying to do:

example1: test intercept + (b1*SOMECONSTANT) = intercept + (b1*SOMECONSTANT) + b2

 

In words, I have a value that I would like to plug into the linear equation to compare these two models to each other.  Essentially, this is comparing two predicted values to each other.

 

I know that I can run the test this way (because I have run this and it works):

example2: test intercept + b1= intercept + b1+ b2

 

But, is there any way to multiply those coefficients (ex. b1) by a number?  Or, conversely, is my 2nd example a satisfactory test?

 

Thank you for any advice!

Erin


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‎01-30-2017 09:59 AM
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Posts: 4

Re: help using TEST in MIANALYZE

Steve (and any others looking for an answer to this question) --

 

I figured it out!

 

You CAN include multipliers in the test statement, you just have to enter them in a specific way...

 

For example, if this is what you are testing:

3*(x1 + x2) + 9*(x3 + x4) = 0

 

You have to type the code this way:

 

test 3*x1 +3*x2 + 9*x3 + 9*x4=0

 

In other words, factor it out.

 

Thanks for all of your help and feedback!

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Respected Advisor
Posts: 2,655

Re: help using TEST in MIANALYZE

I might be missing something obvious here, but why not use TEST b2=0, which comes out with a bit of algebra ?  I would think this would be valid for all values of SOMECONSTANT.

 

If I am missing the obvious, please post back.

 

Steve Denham

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Posts: 4

Re: help using TEST in MIANALYZE

Steve,

Thanks for the reply.

 

I should've used my more complicated example, because what you're saying is accurate.  They would cancel out.

I'll use a few actual numbers here.

 

I have 2 long linear combinations of numbers that I can get down to this formula:

 

9* (x1) + 3*( x4 ) = 0

 

The reason why the 9 and the 3 are important is that they are indicators of time (months), so if I omit those constants, I am allowing x1, for example, to have the same "effect" as x4, for example.  x1 and x4 in this example are each something that reflects a 1 month change.  So in order to talk about the estimated effect of that 9 month time period, I need to multiply x1 by 9.  Similarly in order to talk about the estimated effect of the entire 3 month time period, I need to multiply the x4  by 3.

 

I'm trying to use this test to compare the actual predicted values I calculated.

 

Thanks in advance for any suggestions or comments if I'm thinking about this in the wrong way!

Respected Advisor
Posts: 2,655

Re: help using TEST in MIANALYZE

I would have to noodle this around some to see if it would even work, but what about preprocessing the output dataset from PROC MI to get a new variable that has the effect of getting the response down to what you are interested in, and then applying MIANALYZE to that?  It's the only thing I can think of currently.

 

Steve Denham

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Posts: 4

Re: help using TEST in MIANALYZE

Thanks for responding, Steve.  I'm not quite sure what you're thinking here.

 

I'm using PROC MIXED for my analysis, so what are you thinking about what I could do in that step that would allow me to multiply variables and numbers together in the test statement for MIANALYZE?

 

I had one other alternative idea -- but I'm not sure how this would work either.

 

What if I just ran PROC MIXED on a single imputed data set (really, do it separately for each of my 10 data sets), and then ran some sort of post-estimation test after that? Not even worrying about the MIANALYZE step.   Would there be a way to do my hypothesis tests that way?  Would I have to get creative with the ESTIMATE command?  I haven't used it before, so I'm not sure that could even allow for the multiplication by my 3 and 9.

 

Solution
‎01-30-2017 09:59 AM
New Contributor
Posts: 4

Re: help using TEST in MIANALYZE

Steve (and any others looking for an answer to this question) --

 

I figured it out!

 

You CAN include multipliers in the test statement, you just have to enter them in a specific way...

 

For example, if this is what you are testing:

3*(x1 + x2) + 9*(x3 + x4) = 0

 

You have to type the code this way:

 

test 3*x1 +3*x2 + 9*x3 + 9*x4=0

 

In other words, factor it out.

 

Thanks for all of your help and feedback!

Respected Advisor
Posts: 2,655

Re: help using TEST in MIANALYZE

Mark your answer as correct!

 

Thanks for working this out, Erin.  It will be useful to many, including me.

 

Steve Denham

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