[R] cronbachs alpha - score.items(psych) vs reliability(Rcmdr)

[Doran, Harold]

The alpha.Summary() function in MiscPsycho does this. Here is an example

> xx <- simRasch(200, 10) 
> alpha.Summary(xx$data)
Below is what alpha *would be* if the item were removed 
 
   Item     alpha
1     1 0.5776860
2     2 0.5620276
3     3 0.5336340
4     4 0.5561580
5     5 0.5852708
6     6 0.5875561
7     7 0.5258138
8     8 0.5324561
9     9 0.5285075
10   10 0.5898000 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Christopher W. Ryan
> Sent: Wednesday, February 04, 2009 8:50 AM
> To: r-help at r-project.org
> Subject: Re: [R] cronbachs alpha - score.items(psych) vs 
> reliability(Rcmdr)
> 
> The item.total command in the "multilevel" package will give 
> you what you want.
> 
> --Chris
> Christopher W. Ryan, MD
> SUNY Upstate Medical University Clinical Campus at Binghamton 
> 40 Arch Street, Johnson City, NY  13790 
> cryanatbinghamtondotedu PGP public keys available at 
> http://home.stny.rr.com/ryancw/
> 
> "If you want to build a ship, don't drum up the men to gather 
> wood, divide the work and give orders. Instead, teach them to 
> yearn for the vast and endless sea."  [Antoine de St. Exupery]
> 
> achristoffersen wrote:
> > Dear all,
> > 
> > I like the way the Rcmdr package computes reliability. E.g
> > 
> > reliability(cov(d[,c("q1", "q2", "q3", "q4", "q5", "q6")],
> > use="complete.obs"))
> > 
> > will not only give me the alpha score, but also for each variable, 
> > alpha.score if deleted. However - when writing scripts it's very 
> > tiresome to load the whole Rcmdr GUI just for this purpose. So I'm 
> > looking for an another package that delivers the same feature.
> > 
> > the score.items function in the psych package i find is too 
> > complicated (it requires a keys vector) and it doesn't 
> report the "alpha if deleted" score.
> > 
> > What have I missed when googling for an alternative?
> > 
> > Thx in advance
> > 
> > Andreas
> 
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