>>> El día 01/09/2013 a las 15:13, Helen Sawaya <helensaw...@hotmail.com> escribió: > 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 BIOMECÁNICA DE VALENCIA Universidad Politécnica de Valencia • Edificio 9C Camino de Vera s/n • 46022 VALENCIA (ESPAÑA) 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 Orgánica 15/1999 reguladora de la Protección de Datos de Carácter Personal, le informamos de que el presente mensaje contiene información confidencial, siendo para uso exclusivo del destinatario arriba indicado. En caso de no ser usted el destinatario del mismo le informamos que su recepción no le autoriza a su divulgación o reproducción por cualquier medio, debiendo destruirlo de inmediato, rogándole lo notifique al remitente. ______________________________________________ R-help@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.