[R] PCA sensitive to outliers?

[Joshua Wiley]

On Sun, Apr 22, 2012 at 4:43 PM, Michael <comtech.usa at gmail.com> wrote:
> I actually tried "robustPca" in "pcaMethods" on bioconductor.
>
> It keeps giving me the warning "Input data is not complete"...
>
> Reading into the function:
>
> When there is no "NA"s, it will give this warning...
>
> It seems that there is a bug in this code...
>
> Is it reliable at all?
>
> ---------------------
>
>
>> robustPcafunction (Matrix, nPcs = 2, verbose = interactive(), ...)
> {
>    nas <- is.na(Matrix)
>    if (!any(nas) & verbose) {
>        cat("Input data is not complete.\n")
>        cat("Scores, R2 and R2cum may be inaccurate, handle with care\n")
>    }

that seems to issue the notes when there are *not any missing* and
verbose is TRUE.  I would submit a bug report to the author.

>
>
>
>
>
> On Fri, Apr 20, 2012 at 9:58 AM, Kevin Wright <kw.stat at gmail.com> wrote:
>
>> You can also have a look at the pcaMethods package on Bioconductor.
>>
>> Kevin
>>
>>
>>  On Thu, Apr 19, 2012 at 11:20 PM, Michael <comtech.usa at gmail.com> wrote:
>>
>>>  Hi all,
>>>
>>> I found that the PCA gave chaotic results when there are big changes in a
>>> few data points.
>>>
>>> Are there "improved" versions of PCA in R that can help with this problem?
>>>
>>> Please give me some pointers...
>>>
>>> Thank you!
>>>
>>>        [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
>>
>> --
>> Kevin Wright
>>
>>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.



-- 
Joshua Wiley
Ph.D. Student, Health Psychology
Programmer Analyst II, Statistical Consulting Group
University of California, Los Angeles
https://joshuawiley.com/