PhdPubs {vcdExtra}

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. The higher the number the more prestigious the program.

mentor

number of publications by the mentor in the preceeding three years

Details

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")