C5

.

Is th ere a relationship between the race of violent offenders and the race of their victims? Data from the U.S. Department of Justice for 2011 are presented below.

1. Let’s treat race of offenders as the independent variable and race of victims as the dependent variable. If we first ignore the independent variable and try to predict race of victim, how many errors will we make?
2. If we now take into account the independent variable, how many errors of prediction will we make for those offenders who are white? Black offenders? Other offenders?
3. Combine the answers in

(a) and

(b) to calculate the proportional reduction in error for this table based on the independent variable. How does this statistic improve our understanding of the relationship between the two variables?

Characteristics of Offender Characteristics of Victim White Black White 2,630 448 Other 33 Black 193 2,447 Other 180 45 99 Source: U.S. Department of Justice, Expanded Homicide Data, Table 6, 2011.