[R] Multivariate multiple linear regression question

Virendra Mishra virendra.mishra at gmail.com
Sun Feb 21 09:23:34 CET 2016

```Ok. Will do thank you. I do apologize for the spam. That was done in error.
On Feb 21, 2016 12:10 AM, "Bert Gunter" <bgunter.4567 at gmail.com> wrote:

> Sorry, but please do not multiple post. That's spam.
>
> This is a list about the R programming language, not about statistical
> methods. While there is often some overlap, your questions are entirely
> statistical and therefore OT here( at least imo). Try a statistical list
>
> Cheers,
> Bert
>
>
>
> On Saturday, February 20, 2016, Virendra Mishra <virendra.mishra at gmail.com>
> wrote:
>
>> Hi R-users,
>>
>> I have a fairly simple question to ask but I havent yet got an answer to
>> the question. I will describe my experiment, analysis and what have I done
>> and what is the question in the following paragraphs and I would
>> appreciate
>> if anyone could point me to use right statistical tools to answer my
>> question.
>>
>> Experiment:
>> I have 2 groups and both groups undergo 2 set of evaluations, one with MRI
>> scanner and the other in the lab to test for their behavior. Both these
>> evaluations are known to have statistically significant relationship with
>> age and gender.
>>
>> Statistical question of interest:
>> Whether there is:
>> 1) statistically significant difference between the 2 groups on each
>> evaluation ?
>> 2) Whether there is any relationship between and within the 2 groups
>> between each evaluation
>>
>> Model:
>>
>> I model the problem as following:
>> MRI_measure = Intercept + Slope1 * Age + Slope 2 * Gender + Slope3 * Group
>> [Age is continuous and gender , Group are factors/categorical]
>>
>> Lab_measure = Intercept + Slope1 * Age + Slope 2 * Gender + Slope3 * Group
>> [Age is continuous and gender , Group are factors/categorical]
>>
>> In order to obtain the solution in R:
>> MRI_model<-lm(cbind(MRI_measure, Lab_measure) ~ age+gender+group,
>> data=data)
>>
>> Result of R:
>> manova(MRI_model) suggests that yes indeed all the slopes are
>> significantly
>> different than 0 suggesting a relationship between my measures.
>>
>> Question:
>> 1) In order to test whether the difference in the MRI_measure is
>> statistically significant different between the 2 groups, I use
>> MRI_model\$fitted.values for each dependent measure and do a statistical
>> test (either t-test or Wilcox) and claim that the difference is
>> significant.
>> In the paper I write, multivariate multiple linear regression was
>> performed
>> for the groups while controlling for age and gender. The regressed out
>> MRI_measure was statistically compared to see if the difference is
>> different.
>>
>> I am assuming that the predicted/fitted.values in model are the regressed
>> out variables. Can I show this and use this result? Is this right
>>
>> If no, what is the correct way to statistically compare whether my 2
>> groups
>> differ in their MRI measure and lab measure when controlled for age and
>> gender. Any R library, literature, possibly a script will be greatly
>> appreciated.
>>
>> 2) I also want to see if there is any relationship between MRI_measure and
>> Lab_measure within the group after they are controlled for age and gender.
>> What is the correct way to do this in R?
>>
>> Further, I also want to see if there is any significantly different
>> association between the 2 groups for my set of dependent variables. I am
>> thinking this can be done: I first find the correlation between 2
>> dependent
>> variable in each group and test if this correlation is statistically
>> different between the 2 groups? Is this logic right? And if it is, how do
>> I
>> compare the correlation? If not, what is the right way to do this? Any R
>> library, literature, possibly a script will be greatly appreciated.
>>
>> I do appreciate any reply.
>>
>> Thanks
>>
>> Regards
>>
>> Virendra
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
> --
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along and
> sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>
>

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