[R] Test for equivalence

[Albyn Jones]

testing the null hypothesis of no interaction is not the same as a  
test of equivalence for the two differences.  There is a literature on  
tests of equivalence.  First you must develop a definition of  
equivalence, for example the difference is in the interval (-a,a).   
Then, for example,  you test the null hypothesis that the difference  
is in [a,inf) or (-inf,-a] (a TOST, or two one sided tests).  One  
simple procedure: check to see if the 90% CI for the difference  
(difference of the differences or the interaction effect) is contained  
in the interval (-a,a).

albyn

Quoting Greg Snow <Greg.Snow at imail.org>:

> Does it make sense for you to combine the 2 data sets and do a 2-way  
> anova with treatment vs. control as one factor and experiment number  
> as the other factor?  Then you could test the interaction and  
> treatment number factor to see if they make a difference.
>
> --
> Gregory (Greg) L. Snow Ph.D.
> Statistical Data Center
> Intermountain Healthcare
> greg.snow at imail.org
> 801.408.8111
>
>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
>> project.org] On Behalf Of syrvn
>> Sent: Saturday, February 12, 2011 7:30 AM
>> To: r-help at r-project.org
>> Subject: [R] Test for equivalence
>>
>>
>> Hi!
>>
>> is there a way in R to check whether the outcome of two different
>> experiments is statistically distinguishable or indistinguishable? More
>> preciously, I used the wilcoxon test to determine the differences
>> between
>> controls and treated subjects for two different experiments. Now I
>> would
>> like to check whether the two lists of analytes obtained are
>> statistically
>> distinguishable or indistinguishable
>>
>> I tried to use a equivalence test from the 'equivalence' package in R
>> but it
>> seems that this test is not applicable to my problem. The test in the
>> 'equivalence' package just determines similarity between two conditions
>> but
>> I need to compare the outcome of two different experiments.
>>
>> My experiments are constructed as follows:
>>
>> Exp1:
>> 8 control samples
>> 8 treated samples
>> -> determine significantly changes (List A)
>>
>> Exp2:
>> 8 control samples
>> 8 treated samples
>> -> determine significantly changes (List B)
>>
>>
>> Now i would like to check whether List A and List B are distinguishable
>> or
>> indistinguishable.
>>
>> Any advice is very much appreciated!
>>
>> Best,
>> beginner
>> --
>> View this message in context: http://r.789695.n4.nabble.com/Test-for-
>> equivalence-tp3302739p3302739.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
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>
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>
>