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

PhdPubs

R Documentation

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).

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. The higher the number the more prestigious the program.
mentor: number of publications by the mentor in the preceeding three years

Details

There is a large number of zero counts. Is there evidence for a separate group of non-publishers?

In this version of the data set, phdprestige had been rounded to the nearest integer. A Stata version with the continuous values was subsequently found at https://www.stata-press.com/data/lf2/couart2.dta

Source

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

Long, J. S. & Freese, J. (2006). Regression Models for Categorical Dependent Variables Using Stata, 2nd Ed., Stata Press.

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")

vcdExtra documentation built on Dec. 11, 2025, 9:06 a.m.