case1902 {Sleuth2} | R Documentation |
Lawyers collected data on convicted murderers in the state of Georgia to see whether convicted murderers who were black were more likely to receive the death penalty than convicted murderers who were white, after accounting for aggravation level of the murder. They categorized murders into 6 progressively more serious types. Category 1 comprises barroom brawls, liquor-induced arguments lovers' quarrels, and similar crimes. Category 6 includes the most vicious, cruel, cold=blooded, unprovoked crimes.
case1902
A data frame with 12 observations on the following 4 variables.
Aggravation
"1"
, "2"
, "3"
, "4"
,
"5"
and "6"
Victim
"White"
and "Black"
Death
Nodeath
Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A Course in Methods of Data Analysis (2nd ed), Duxbury.
Woodworth, G.C. (1989). Statistics and the Death Penalty, Stats 2: 9–12.
str(case1902) # Add smidgeon to denominator because of zeros empiricalodds <- with(case1902, Death/(Nodeath + .5)) plot(empiricalodds ~ as.numeric(Aggravation), case1902, log="y", pch=ifelse(Victim=="White", 21, 19), xlab="Aggravation Level of the Murder", ylab="Odds of Death Penalty") legend(3.8,.02,legend=c("White Victim Murderers","Black Victim Murderers"),pch=c(21,19)) fitbig <- glm(cbind(Death,Nodeath) ~ Aggravation*Victim, case1902, family=binomial) # No evidence of overdispersion; no statistically significant evidence # of interactive effect anova(fitbig, test="Chisq") fitlinear <- glm(cbind(Death,Nodeath) ~ Aggravation + Victim, case1902, family=binomial) summary(fitlinear) # Mantel Haenszel Test, as an alternative table1902 <- with(case1902, rbind(Death,Nodeath)) dim(table1902) <- c(2,2,6) mantelhaen.test(table1902)