Vijayan, I cannot find an error in your code, but I had a look at the code of triangle.test -- unless I'm missing something, it contains a bug. If you study the way in which the matrix "pref" is updated, you find that the vector preference is compared to 1, 2 and 3 instead of "X", "Y" and "Z" as it should be. That way, some of the non-diagonal entries of pref will always be zero, irrespective of the data, which does not make sense. I think it should work if you modify the code accordingly. Alternatively, a quick patch (untested!) might be to code preferences as 1, 2 and 3 instead of the letters (but I'm not sure whether this has any other implications). I CC the author of the function and maintainer of the package; he should correct me if needed or could otherwise update the code for the next release (I worked on SensoMineR 1.11).
Hope this helps, Michael > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Vijayan Padmanabhan > Sent: Saturday, June 04, 2011 9:21 > To: r-help@r-project.org > Subject: [R] library(SenoMineR)- Triangle Test Query > > Dear R Group > I was trying to use the triangle.test function in SensoMineR and > strangely i > encounter a error in the output of preference matrix from the analysis. > To illustrate, pl see the following dataframe of a design with the > response > and preference collected as shown below: > > design<-structure(list(`Product X` = c(3, 1, 4, 2, 4, 2, 1, 3, 4, 2, > 4, 2, 1, 3, 4, 2, 4, 2, 3, 1), `Product Y` = c(1, 1, 4, 4, 4, > 3, 1, 1, 4, 4, 4, 3, 1, 1, 4, 4, 4, 3, 1, 1), `Product Z` = c(3, > 2, 1, 2, 3, 3, 2, 3, 1, 2, 3, 3, 2, 3, 1, 2, 3, 3, 3, 2), Response = > structure(c(1L, > 2L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, > 1L, 1L, 2L), .Label = c("X", "Z"), class = "factor"), Preference = > structure(c(1L, > 3L, 1L, 1L, 1L, 2L, 3L, 1L, 1L, 1L, 1L, 2L, 3L, 1L, 1L, 1L, 1L, > 2L, 1L, 2L), .Label = c("X", "Y", "Z"), class = "factor")), .Names = > c("Product X", > "Product Y", "Product Z", "Response", "Preference"), class = > "data.frame", > row.names = c("Panelist1.Test1", > "Panelist1.Test2", "Panelist2.Test1", "Panelist2.Test2", > "Panelist3.Test1", > "Panelist3.Test2", "Panelist4.Test1", "Panelist4.Test2", > "Panelist5.Test1", > "Panelist5.Test2", "Panelist6.Test1", "Panelist6.Test2", > "Panelist7.Test1", > "Panelist7.Test2", "Panelist8.Test1", "Panelist8.Test2", > "Panelist9.Test1", > "Panelist9.Test2", "Panelist10.Test1", "Panelist10.Test2")) > > If you were to investigate the above dataframe, you would find that for > the > comparision of Product 2 Vs Product 3, the preference indicates product > 3 is > preferred over product 2 all the time. > > ## Read output from the following script to see what i mean above: > subset(design,`Product X`==2&`Product Y`==3&`Product Z`==3) > > ##Output of above would be: > . Product X Product Y Product Z Response Preference > Panelist3.Test2 2 3 3 X Y > Panelist6.Test2 2 3 3 X Y > Panelist9.Test2 2 3 3 X Y > > However when I analyse the design with the answers and preferences > using the > following script, I get the $pref output which shows that product 2 is > preferred over 3 all the time. Can somebody explain what is wrong in my > script? > > answer<-as.vector(design$Response) > preference<-as.vector(design$Preference) > triangle.test (design[,1:3], answer,preference) > > ##$pref output from the triangle.test function shows as follows: > > $pref > 1 2 3 4 > 1 0 0 0 0 > 2 4 0 3 0 > 3 0 0 0 0 > 4 0 0 0 0 > > > Any help in helping me identify what is going wrong here would be > highly > appreciated. > Regards > Vijayan Padmanabhan > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
