>>> El d?a 01/09/2013 a las 15:13, Helen Sawaya
<helensawaya at hotmail.com>
escribi?:> Dear R experts,
> I have data from a questionnaire that I would like to factor analyse.
It is > in a likert scale form (0-3). I would like to check first for
univariate and > multivariate outliers but the most common ways of doing so assume the
data is > continuous and normal- neither of which is the case here. I found an
article > discussing this (Outlier Detection in Test and Questionnaire Data by
Wobbe P. > Zijlstra, L. Andries van der Ark, and Klaas Sijtsma), but I was
wondering if > I could get the exact R code on how to implement the outlier
detection > analyses.
I have not found an exact implementation of that article, but one of
its authors (van den Ark) has published the "mokken" package with some
methods referred to in it:
https://sites.google.com/a/tilburguniversity.edu/avdrark/mokken
The ESD method for identifying outliers, also used in the paper to
handle outlier scores, is implemented (together with others) in the
package "parody":
http://www.bioconductor.org/packages/release/bioc/html/parody.html
Hope it helps
Helios De Rosario
INSTITUTO DE BIOMEC?NICA DE VALENCIA
Universidad Polit?cnica de Valencia ? Edificio 9C
Camino de Vera s/n ? 46022 VALENCIA (ESPA?A)
Tel. +34 96 387 91 60 ? Fax +34 96 387 91 69
www.ibv.org
Antes de imprimir este e-mail piense bien si es necesario hacerlo.
En cumplimiento de la Ley Org?nica 15/1999 reguladora de la Protecci?n
de Datos de Car?cter Personal, le informamos de que el presente mensaje
contiene informaci?n confidencial, siendo para uso exclusivo del
destinatario arriba indicado. En caso de no ser usted el destinatario
del mismo le informamos que su recepci?n no le autoriza a su divulgaci?n
o reproducci?n por cualquier medio, debiendo destruirlo de inmediato,
rog?ndole lo notifique al remitente.