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List:       r-help
Subject:    Re: [R] arcsine transformation
From:       Chuck Cleland <ccleland () optonline ! net>
Date:       2008-04-30 23:24:26
Message-ID: 4818FFAA.3 () optonline ! net
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On 4/30/2008 4:52 PM, Claire Sheller wrote:
> I have been trying to preform both a bartlett's test and an arcsine
> transformation on some average percentage data. I've tried inputting it
> different ways and I keep getting the same error message:
> 
>> head(workingdata)
>    DYAD   BEFORE     AFTER
> 1 BG-FL 4.606772  5.787520
> 2 BG-LL 5.467503  7.847395
> 3 AD-MV 5.333735 11.107380
> 4 MM-FL 5.578708 12.063500
> 5 MM-MV 2.037605  6.415303
> 6 MM-RM 6.158885 11.911080
>> bartlett.test(BEFORE ~ AFTER)
> Error in bartlett.test.default(c(4.606772, 5.467503, 5.333735, 5.578708,  :
>   there must be at least 2 observations in each group

   bartlett.test() expects the second argument to be "a vector or factor 
object giving the group for the corresponding elements of x".  You seem 
to have paired samples instead.

>> asin(BEFORE)
> [1] NaN NaN NaN NaN NaN NaN NaN
> Warning message:
> In asin(BEFORE) : NaNs produced

   You might divide the values by 100 prior to asin().

> I'm at a loss here and I would greatly appreciate any guidance that could be
> given me. Thank you! 

-- 
Chuck Cleland, Ph.D.
NDRI, Inc. (www.ndri.org)
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
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