[R] Info

[Prof Brian Ripley]

Also, factanal() does not do `principal component analysis', and it may 
well be that the data are inappropriate for factor analysis if they are 
appropriate for PCA.

If PCA was really intended, prcomp() and princomp() are appropriate tools.

On Tue, 30 Nov 2004, Andy Bunn wrote:

> It looks like factanal is unable to optimize from these starting values
> (kinda like the error message says). So, factanal.fit.mle isn't converging
> and you have problems with your analysis. Try putting control = list(trace =
> T) in your code to see what happenens. E.g.,
>
> R >
> R >      v1 <- c(1,1,1,1,1,1,1,1,1,1,3,3,3,3,3,4,5,6)
> R >      v2 <- c(1,2,1,1,1,1,2,1,2,1,3,4,3,3,3,4,6,5)
> R >      v3 <- c(3,3,3,3,3,1,1,1,1,1,1,1,1,1,1,5,4,6)
> R >      v4 <- c(3,3,4,3,3,1,1,2,1,1,1,1,2,1,1,5,6,4)
> R >      v5 <- c(1,1,1,1,1,3,3,3,3,3,1,1,1,1,1,6,4,5)
> R >      v6 <- c(1,1,1,2,1,3,3,3,4,3,1,1,1,2,1,6,5,4)
> R >      m1 <- cbind(v1,v2,v3,v4,v5,v6)
> R >      factanal(m1, factors=3, control = list(trace = T))
> start 1 value: 0.4755156 uniqs: 0.0050 0.1009 0.0050 0.2241 0.0843 0.0050
>
> Call:
> factanal(x = m1, factors = 3, control = list(trace = T))
>
> Uniquenesses:
>   v1    v2    v3    v4    v5    v6
> 0.005 0.101 0.005 0.224 0.084 0.005
>
> Loadings:
>   Factor1 Factor2 Factor3
> v1 0.944   0.182   0.267
> v2 0.905   0.235   0.159
> v3 0.236   0.210   0.946
> v4 0.180   0.242   0.828
> v5 0.242   0.881   0.286
> v6 0.193   0.959   0.196
>
>               Factor1 Factor2 Factor3
> SS loadings      1.893   1.886   1.797
> Proportion Var   0.316   0.314   0.300
> Cumulative Var   0.316   0.630   0.929
>
> The degrees of freedom for the model is 0 and the fit was 0.4755
> R >
>
> If you think the model should be OK and there isn't an error somewhere else
> then you'll want to fiddle with the control options. From the help for
> fractanal:
>
> control: A list of control values,
>
>          nstart The number of starting values to be tried if 'start =
>               NULL'. Default 1.
>
>          trace logical. Output tracing information? Default 'FALSE'.
>
>          lower The lower bound for uniquenesses during optimization.
>               Should be > 0. Default 0.005.
>
>          opt A list of control values to be passed to 'optim''s
>               'control' argument.
>
>          rotate a list of additional arguments for the rotation
>               function.
>
>     ...: Components of 'control' can also be supplied as named
>          arguments to 'factanal'.
>
>
> HTH, Andy
>
>
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch]On Behalf Of Catherine Dempsey
>> Sent: Tuesday, November 30, 2004 7:31 AM
>> To: 'r-help at lists.R-project.org'
>> Subject: [R] Info
>>
>>
>> I am having difficulty obtaining the scores from my principal component
>> analysis.  I have used this method before and have had no problems.  The
>> data set that I am using this time is similar to what I have used in the
>> past.  What do I need to do to my dataset in order for me to obtain these
>> scores?
>>
>> R screen says the following message
>>
>> Error in factanal(covmat = pasa.cov, factors = 4) :
>>         Unable to optimize from these starting value(s)
>>
>> many thanks
>>
>> Catherine
>>
>>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595