2: Defining and Measuring Crime 
and Criminal Justice 
Learning Objectives 
In the previous section, we spent much time trying to understand how to define crime, whereas this section will 
focus on the task of measuring crime. Measuring crime is quite complex and requires an understanding of different 
data sets and how we use them. Defining crime seems complex, but measuring crime is just as complicated of a task. 
Without crime, there is no need for the criminal justice system. We must have a clear and accurate understanding 
of crime in order to create effective policies to combat it or help minimize it. This section will teach students how 
to obtain accurate measures of crime so that they can be an informed citizen. Further, if we have an accurate picture 
of crime and trends, we can better predict the needs of our society, such as increased patrol, rehabilitation services, 
and more. We will also spend some time talking about evidence-based practices, discussed in greater detail later. 
After reading this section, students will be able to: 
• 
Develop an understanding of the different data sources used to gather precise and accurate measures 
of crime 
• 
Recognize the difference between official or reported statistics, self-report statistics, and victimization 
statistics 
• 
Evaluate the reliability of statistics and data heard about the criminal justice system 
Critical Thinking Questions 
1. 
What are the three different types of data sources we often rely on in CJ? 
2. 
What are the strengths and limitations of each data source? 
3. 
Identify when each type of data source would be appropriate for different crimes and why. 
 
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