Am 14.09.2007 um 12:05 schrieb Peter Dalgaard:
> S Ellison wrote:
>>
>>>>> Peter Dalgaard <[EMAIL PROTECTED]> 14/09/2007 09:26:16 >>>
>>>>>
>>>> So what can I do now to solve my problem?
>>>>
>>>> Do you think I should not use paired=TRUE?
>>>>
>>> You *can* only use it when you have pairs, and you must do it
>>> then, to
>>> correct for intra-pair correlation. The drawback is that it looks
>>> only
>>> at complete pairs, throwing away all the singlets. It is possible to
>>> recover the information from the singlets , basically by combining a
>>> paired test for the pairs and an unpaired one for the singlets.
>>> (Someone
>>> must have written this down, but I'm afraid I don't have a nice
>>> reference).
>>>
>>
>> Question: Could you achieve this kind of outcome with lme? stack
>> the two groups, mark the observations y by subject (ie the pair
>> ID) and group (treatment, presumably), and do something like
>>
>> anova(lme(y~group, data=d, random=~1|subj, na.action=na.omit))
>>
>> Or is that just disguising one of those nasty unbalanced 2-way
>> anova problems?
>>
> Yes, but....
>
> I don't think lme() will do better than what you can do by hand:
> Get two
> independent estimates of mu1-mu2 (one estimate from the pairs and one
> from the singlets), compute a weighted average using the s.e.'s and
> test
> that against zero (possibly after testing them for equality for good
> measure). This is easy if you use a plug-in approach: first assume
> that
> the s.e. are known, then plug in their empirical value. The tricky bit
> is to calculate the DF in the style of Welch's test.
I apologise but I really can not follow your
explanations. I am R
and Stastistics Beginner.
What do you mean with mu1-mu2 and what are s.e.´s?
Once again thank you for your help.
Birgit
>
> --
> O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
> c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
> (*) \(*) -- University of Copenhagen Denmark Ph: (+45)
> 35327918
> ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45)
> 35327907
>
>
Birgit Lemcke
Institut für Systematische Botanik
Zollikerstrasse 107
CH-8008 Zürich
Switzerland
Ph: +41 (0)44 634 8351
[EMAIL PROTECTED]
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