GLM repeated misures?

GLM repeated misures?

Post by Guid » Mon, 28 Jul 2003 01:06:52



Hi
sorry for my english.
i hope you can help me about this problem.
There are three groups (group A, 12 cases; group B, 8 cases; group C,
Control, 8 cases).
I survey those variables: Age, School, Sex, treatment F, treatment G.
I want investigate if (and how) the treatment F and the treatment G are
influenced by the tipe of group (A, B, C), with Age covariate variable.

how can i do it?
And wich is the main result of the analysis?

i tryed to use the menu Analyze-GLM-repeated mesures, but i'm not sure abuot
the results i obtained.

Thanks!

G.G.

 
 
 

GLM repeated misures?

Post by Rich Ulric » Tue, 29 Jul 2003 05:46:01




Quote:> Hi
> sorry for my english.
> i hope you can help me about this problem.
> There are three groups (group A, 12 cases; group B, 8 cases; group C,
> Control, 8 cases).
> I survey those variables: Age, School, Sex, treatment F, treatment G.
> I want investigate if (and how) the treatment F and the treatment G are
> influenced by the tipe of group (A, B, C), with Age covariate variable.

> how can i do it?
> And wich is the main result of the analysis?

> i tryed to use the menu Analyze-GLM-repeated mesures, but i'm not sure abuot
> the results i obtained.

"repeated measures"  would be something like:   pre-post on
each person; or some set of parallel outcomes.  You say
"treatment"  but you do not mention Pre  measures, which
could help the power.

How are you involved with this?
 - Isn't there someone around who has experience?

It is not impossible to learn something about "statistics"  by
running a stat-package, but if you haven't had any classroom
experience, or exposure to research reports, my advice is
"Take a course"  and "Do a lot of reading."  (The quicker
introduction, maybe, is from some person near you who
will give personal help and advice.)

Start with individual correlations.  Do one-way ANOVA.  
Eventually do multi-way ANOVA  and use a covariate.

--

http://www.pitt.edu/~wpilib/index.html
"Taxes are the price we pay for civilization."  Justice Holmes.

 
 
 

GLM repeated misures?

Post by Guid » Tue, 29 Jul 2003 07:42:20


Quote:> > Hi
> > sorry for my english.
> > i hope you can help me about this problem.
> > There are three groups (group A, 12 cases; group B, 8 cases; group C,
> > Control, 8 cases).
> > I survey those variables: Age, School, Sex, treatment F, treatment G.
> > I want investigate if (and how) the treatment F and the treatment G are
> > influenced by the tipe of group (A, B, C), with Age covariate variable.

> > how can i do it?
> > And wich is the main result of the analysis?

> > i tryed to use the menu Analyze-GLM-repeated mesures, but i'm not sure
abuot
> > the results i obtained.

> "repeated measures"  would be something like:   pre-post on
> each person; or some set of parallel outcomes.  You say
> "treatment"  but you do not mention Pre  measures, which
> could help the power.

> How are you involved with this?
>  - Isn't there someone around who has experience?

> It is not impossible to learn something about "statistics"  by
> running a stat-package, but if you haven't had any classroom
> experience, or exposure to research reports, my advice is
> "Take a course"  and "Do a lot of reading."  (The quicker
> introduction, maybe, is from some person near you who
> will give personal help and advice.)

> Start with individual correlations.  Do one-way ANOVA.
> Eventually do multi-way ANOVA  and use a covariate.

Thanks a lot.

I'm a statician but i never used SPSS; i used just R, often for economics
problems.
A friend asked me about the question in object (using spss!!!) and i
searched the answer in this newsgroup.
Thanks for the advices.

G.G.

- Show quoted text -

> --

> http://www.pitt.edu/~wpilib/index.html
> "Taxes are the price we pay for civilization."  Justice Holmes.

 
 
 

1. what is assumption for repeated measures analysis using proc GLM, MIXED, GENMOD?

For continued response data.

As we learned that there are three assumption for employ ANOVA:
independent observations
normally distributed data for each group
equal variances for each group

But for REPEATED MEASURES data the first one will be violated so we us
some appoaches to accourt for the correction. but the rest two
assumptions should still be met or not?

for example,

person    Before    Drug_A    Drug_B    Drug_C

  1         94        67         90       67
  2         57        52         69       55
  3         81        74         69       73
  4         82        59         71       72
  5         67        65         74       72
  6         78        72         80       72
  7         87        75        106       74
  8         82        68         76       59
  9         90        74         82       80
....

<this is a cross-over study design, the three drug are measured at the
same subject four times. the response variable is heart reate, the
DRUG B is placebo>

my code is;

PROC GLM DATA=mydata;
        MODEL Before Drug_A Drug_B Drug_C =/NOUNI ;
        REPEATED hrate 4 CONTRAST(1)/ PRINTE SUMMARY;
        REPEATED hrate 4 CONTRAST(4)/ PRINTE SUMMARY;
RUN;QUIT;

then i got a output about the spericity test and something else. but
any other thing i forgot? are ther other assumption should be tested?

Any suggestion or reference are appreciated! thanks in advance.

Johson Chang

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