You can also explore the classical() function in the MiscPsycho package that does item analysis.
> -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf Of Iasonas Lamprianou > Sent: Wednesday, December 01, 2010 4:52 AM > To: Michael Bedward; ivan.calan...@uni-hamburg.de; Rhelp > Subject: Re: [R] missing values > > thank you, I'll have a go and let you know if i have problems > Dr. Iasonas Lamprianou > > > > > Assistant Professor (Educational Research and Evaluation) > Department of Education Sciences > European University-Cyprus > P.O. Box 22006 > 1516 Nicosia > Cyprus > Tel.: +357-22-713178 > Fax: +357-22-590539 > > > > > Honorary Research Fellow > Department of Education > The University of Manchester > Oxford Road, Manchester M13 9PL, UK > Tel. 0044 161 275 3485 > iasonas.lampria...@manchester.ac.uk > > > > ----- Original Message ---- > From: Michael Bedward <michael.bedw...@gmail.com> > To: ivan.calan...@uni-hamburg.de; lampria...@yahoo.com; Rhelp > <r-help@r-project.org> > Sent: Wed, 1 December, 2010 11:40:13 > Subject: Re: [R] missing values > > And just to add to Ivan's comment, if you are using the rowSums or > colSums functions with a matrix or data.frame they also have the na.rm > argument. > > Michael > > On 1 December 2010 20:16, Ivan Calandra <ivan.calan...@uni-hamburg.de> wrote: > > Hi, > > > > (a) sum() and mean() have a na.rm argument that should be set to TRUE. > > > > (b) let's try with an example: > > x <- c(1:5, NA, NA, 6:10, NA) > > x[is.na(x)] <- 0 ## replace NAs by 0 > > > > HTH, > > Ivan > > > > > > Le 12/1/2010 10:00, Iasonas Lamprianou a écrit : > >> > >> Dear all, > >> i have spent a lot of time trying to solve this problem, but I am sure > >> that > >> there must be a simple solution. So, as a last resort, I am coming back to > >> you > >> again. I have a dataset with some (almost random) values in many > >> variables. Lets > >> say that the dataset represents the scores of students to test questions. > >> What I > >> need to do is to sum the scores for each student. However, wherever there > >> is a > >> missing (NA) value, I cannot get the total score. How can I compute the > >> total > >> score and the average per question (a) by ignoring the missing responses, > >> (b) by > >> assuming that a missing response is a zero? > >> Thank you for the response > >> > >> > >> Dr. Iasonas Lamprianou > >> > >> > >> > >> > >> Assistant Professor (Educational Research and Evaluation) > >> Department of Education Sciences > >> European University-Cyprus > >> P.O. Box 22006 > >> 1516 Nicosia > >> Cyprus > >> Tel.: +357-22-713178 > >> Fax: +357-22-590539 > >> > >> > >> > >> > >> Honorary Research Fellow > >> Department of Education > >> The University of Manchester > >> Oxford Road, Manchester M13 9PL, UK > >> Tel. 0044 161 275 3485 > >> iasonas.lampria...@manchester.ac.uk > >> > >> > >> > >> > >> > >> ______________________________________________ > >> 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. > >> > > > > -- > > Ivan CALANDRA > > PhD Student > > University of Hamburg > > Biozentrum Grindel und Zoologisches Museum > > Abt. Säugetiere > > Martin-Luther-King-Platz 3 > > D-20146 Hamburg, GERMANY > > +49(0)40 42838 6231 > > ivan.calan...@uni-hamburg.de > > > > ********** > > http://www.for771.uni-bonn.de > > http://webapp5.rrz.uni-hamburg.de/mammals/eng/1525_8_1.php > > > > ______________________________________________ > > 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. > > > > > > > > ______________________________________________ > 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. ______________________________________________ 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.
