[R] Bartlett Test

[David Winsemius]

On Mar 1, 2010, at 12:12 PM, Amit Patel wrote:

> Apparently the vectors that I have are lists

Then unlist them.

> and when I try to conduct the Bartlett test I am getting errors. I  
> may be using it wrong. I am not an R expert>
>
> xbartlett2 <- c(Samp1,Samp2)
> #Samp1 & 2 are lists
> gbartlett24 <- c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2,  
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2)
>
> Attempt 1
>> gazant <- bartlett.test(xbartlett2~gbartlett24)$p.value
> Error in model.frame.default(formula = xbartlett2 ~ gbartlett24) :
>  invalid type (list) for variable 'xbartlett2'
>
> xbartlett2 <- c(Samp1,Samp2)
>
>
>
>> gazant <- bartlett.test(xbartlett2, gbartlett24)$p.value
> Error in bartlett.test.default(xbartlett2, gbartlett24) :
>  there must be at least 2 observations in each group
>
> (There are at least 2 unique observations in each group)
>
> Thanks in advance
>
>
>
>
>
> ----- Original Message ----
> From: "Richardson, Patrick" <Patrick.Richardson at vai.org>
> To: Amit Patel <amitrhelp at yahoo.co.uk>; "r-help at r-project.org" <r-help at r-project.org 
> >
> Sent: Mon, 1 March, 2010 14:31:15
> Subject: RE: [R] Bartlett Test
>
> ?bartlett.test
>
> From the help page "If x is a list, its elements are taken as the  
> samples or fitted linear models to be compared for homogeneity of  
> variances. In this case, the elements must either all be numeric  
> data vectors or fitted linear model objects, g is ignored, and one  
> can simply use bartlett.test(x) to perform the test. If the samples  
> are not yet contained in a list, use bartlett.test(list(x, ...)).
>
> Otherwise, x must be a numeric data vector, and g must be a vector  
> or factor object of the same length as x giving the group for the  
> corresponding elements of x. "
>
> Patrick
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org 
> ] On Behalf Of Amit Patel
> Sent: Monday, March 01, 2010 9:26 AM
> To: r-help at r-project.org
> Subject: [R] Bartlett Test
>
> Hi
>
> I am trying to conduct a Bartlett test between two groups Samp 1 and  
> Samp 2, both of which are vectors of equal length. I cant find any  
> information on how to do this. Does the data need to be in a  
> structured list.
>
> Thanks in advance
>
>
>
>
>
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