Chapter 4: Measurement and Units of Analysis

Learning Objectives

  • Differentiate between validity and reliability.
  • Explain the difference between internal and external validity.
  • Examine the difference between a variable and an attribute.
  • Define and provide examples for each of the four level of measurement: nominal, ordinal, interval, ratio.
  • Explain the difference between the independent and dependent variable.
  • Describe an extraneous variable and explain how it can threaten research findings.
  • Discuss what is meant by a rival plausible explanation.
  • Explain what a hypothesis is and in what situations creating a hypothesis is a suitable approach.

How do we know that our measures are good? Without some assurance of the quality of our measures, we cannot be certain that our findings have any meaning or, at the least, that our findings mean what we think they mean. When social scientists measure concepts, they aim to achieve reliability and validity in their measures. These two aspects of measurement quality are the focus of the first section in this chapter. We will consider reliability first and then take a look at validity. For this section, imagine we are interested in measuring the concepts of alcoholism and alcohol intake. What are some potential problems that could arise when attempting to measure this concept, and how might we work to overcome those problems?