vcdExtra (version 0.6-5)

PhdPubs: Publications of PhD Candidates

Description

A data set giving the number of publications by doctoral candidates in biochemistry in relation to various predictors, originally from Long (1997). There is a large number of zero counts. Is there evidence for a separate group of non-publishers?

Usage

data(PhdPubs)

source

Long, J. S. (1997) Regression Models for Categorical and Limited Dependent Variables, Sage.

Examples

data(PhdPubs)
# very uninformative
hist(PhdPubs$articles, breaks=0:19, col="pink", xlim=c(0,20),
     xlab="Number of Articles")

library(vcd)
rootogram(goodfit(PhdPubs$articles), xlab="Number of Articles")
# compare with negative binomial
rootogram(goodfit(PhdPubs$articles, type="nbinomial"), 
	xlab="Number of Articles", main="Negative binomial")