jester | R Documentation |
A likelihood function for the Jester datasets
data(jester)
Object jester
is a likelihood function for the 91 jokes rated by
the first 150 respondents in file ‘jester_dataset_1_3.zip’, taken
from Goldberg et al. Object jester_maxp
is the result of running
maxp(jester)
. The results table of (nearly) all jokes and
respondents is given as jester_table
in which each row is a joke
and each column a respondent.
The dataset is interesting because it has been analysed by many workers,
including Goldberg, for patterns; here I assume that all the respondents
behave identically (but randomly). It is included here because it is a
very severe numerical challenge in the context of the hyper2
package. I am not convinced that maxjest
is even close to the
true evaluate.
Objects jester
, jester_table
, and jester_maxp
can
be generated by running script ‘inst/jester.Rmd’, which includes
some further technical documentation. This file takes about 10 minutes
to run.
Eigentaste: A Constant Time Collaborative Filtering Algorithm. Ken Goldberg, Theresa Roeder, Dhruv Gupta, and Chris Perkins. Information Retrieval, 4(2), 133-151. July 2001.
# maxp(jester) # takes too long
# Note that the possibly poor identification of the evaluate
# nevertheless allows us to reject the null of equality:
(LAM <- -2*(loglik(equalp(jester),jester)-loglik(jester_maxp,jester)))
pval <- pchisq(LAM,df=size(jester),lower.tail=FALSE)
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