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| Author: |
z |
| Subject: |
Re: Nonparametric longitudinal analysis |
| Body: |
On May 12, 11:13=A0am, W <wzhang...@gmail.com> wrote:
> On May 9, 6:35=A0pm, Richard Ulrich <Rich.Ulr...@comcast.net> wrote:
>
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>
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> > On Fri, 9 May 2008 13:42:35 -0700 (PDT), W <wzhang...@gmail.com>
> > wrote:
>
> > > Hi All:
>
> > > I have a longitudinal data with 2 factors: starin and age, and a
> > > covariate bodyweight. Each subject was measured at 0min, 30min, 60min,=
> > > 90min and 120 min.
>
> > That sounds simple enough, but I have no idea what
> > "starin" is (and Google doesn't help). =A0Thus, I have no
> > natural notion of what is being measured, and whether it
> > grows/ sinks =A0rapidly, or what.
>
> > You can usually get better advice when we readers have
> > a better idea of what you are trying to accomplish, and
> > with what data.
>
> I apologize. "starin" should be "Strain".
>
> This was an experiment of glucose tolorence test on mice. Glucose was
> measured at 0, 30, 60, 90 and 120minutes. The mean at each tome point
> was about 177, 537, 516, 512, 508. Time 0 is when glucose was applied.
>
>
>
> > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0The data were q=
uite right-skewed due to
> > > truncation(the lab machine can only read up to 600unit).
>
> > "Right-skewed" in statistics means that there is the
> > long tail to the right, with the bulk of data on the left.
> > I think you describe "left-skewed". =A0(This does contradict
> > a certain natural-language use of skewness, such as,
> > "attitudes skewed towards Democratic" which would place
> > the bulk as Democratic.)
>
> Apologize again. I mean it's left-skewed. The response was truncated
> at 600 (81 out of 240), which was the ceiling the machine can read.
> The Skewness was -0.71 and the Kurtosis was -1.1. Do you think I can
> still do the analyses as you proposed above? One thing I was not sure
> was how I can handle the correlated structure of the repeated measures
> at the 5 time points, which can be easily taken care of by sas proc
> mixed if I have a normality assumption for the reponse.- Hide quoted text =
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>
> - Show quoted text -
what exactly are you trying to prove/disprove/study?
with data that hits a ceiling like that, you are definitely limited to
certain tests. which i'm trying to remember, having done a lot of this
a while back. Sign test?
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| Topic: |
Nonparametric longitudinal analysis |
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| Message: |
Author |
Date |
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*Message 1* |
z |
Mon, 12 May 2008, 1:03 pm |
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