Criminal Justice Research  

Application: Measuring Variables

Measurement is one of the foundational aspects of science and knowledge. It allows researchers, once they have defined and conceptualized their variables, to measure (not just observe) them in order to conduct analysis. How well variables (i.e., phenomena) are defined and measured affects what can be known about them and the overall validity of that research as a whole. Judgments about evidence to support a particular intervention are not just about the demonstration of successful outcomes but also entail considerations about the quality of the measures of these outcomes.

Measurement scales are distinguished by their level: nominal, ordinal, interval, or ratio. A variable can have any of these levels. For example, a variable that has a nominal-level measurement scale is commonly referred to as a nominal-level variable or, simply, a nominal variable. There are many factors to consider when choosing a particular level of measurement and so it is important to make sure you are using the correct level of measurement when conducting a research study. The measurement chosen can support whether your study is valid and reliable.

For this Application Assignment, consider the differences between measurement and observation. Then think about the differences between and among nominal, ordinal, interval, and ratio levels of measurement and why it is important to know the level(s) of measurement in a study. Finally, consider how you might improve the validity and reliability of variable conceptualization and measurement.

The assignment (2-3 pages):

• Explain differences between measurement and observation.
• Explain differences between the four levels of measurement: nominal, ordinal, interval, and ratio.
• Explain why it is important to know the level(s) of measurement for variables in a study.
• Describe two techniques that may be used to improve the validity and reliability of variable measurement.