The Relationship Between Reliability & Validity

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  • 0:05 Measurement
  • 0:56 Reliability vs. Validity
  • 3:14 Relationship
  • 5:17 Lesson Summary
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Lesson Transcript
Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

Though reliability and validity are different from each other, they are still related. In this lesson, we'll look at the differences of and relationship between reliability and validity.


Imagine that you are a psychologist, and you want to study the relationship between stereotyped thinking and critical thinking. You believe that people who think in terms of stereotypes will have lower critical thinking skills than people who do not employ stereotypes in their thinking. But, how do you know whether a person thinks in terms of stereotypes or not? How do you know if they have high critical thinking skills?

Psychological measurement is the process of assessing psychological traits. These could be things like stereotyped thinking or critical thinking skills, or they could be traits, like anxiety, optimism or intelligence. When measuring anything, there are two major issues that need to be taken into account: reliability and validity. Let's look closer at both of them and how they are related to each other.

Reliability vs. Validity

You wake up one morning and step on the scale. It reads '117,' which you think is too low. You step off the scale and back on again, and it reads '143.' Okay, well, that's better, but just to be sure, you step off and back on for a third time. This time, the scale reads '108.'

I hate to break the bad news, but your scale is not reliable. Reliability is the extent to which a measurement tool gives consistent results. If your scale read '143' every time you stepped on it, it would be reliable. But, notice that the scale doesn't have to be right to be reliable; it just has to produce consistent results. For example, if your scale read '108' every single time you stepped on it, but you really weigh 143, your scale is reliable even though it's not correct.

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