PhdPubs: Publications of PhD Candidates
In vcdExtra: 'vcd' Extensions and Additions

Description Usage Format Source Examples

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?

1	data(PhdPubs)

A data frame with 915 observations on the following 6 variables.

articles: number of articles published in the final three years of PhD studies
female: dummy variable for gender, coded 1 for female
married: dummy variable for marital status, coded 1 for married
kid5: number of young children, age 5 and under
phdprestige: prestige of the PhD department
mentor: number of publications by the mentor in the preceeding three years

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

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")