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)

Format

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

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")