The Reliability of Measurement: Definition, Importance & Types

The Reliability of Measurement: Definition, Importance & Types
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  • 0:05 Measurement
  • 1:28 Reliability
  • 3:01 Types
  • 4:41 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.

Psychologists use tools like surveys and tests to measure psychological traits. But, what happens when a measurement tool is not consistent? In this lesson, we'll examine what reliability is, why it is important, and some major types.


Jodie has noticed something about the people she encounters. It seems like the people she meets who have either a very large or small amount of education are not very racist. But, the people in the middle - those who have some advanced education but not a lot - seem to be racist. What's going on? Jodie wants to design a research study to see if this is normal. She wonders if people with racist attitudes have high, low, or medium educational levels on average.

In order to figure out the relationship between education and racism, Jodie has to measure her two variables. She can find out educational level pretty easily by asking people how much education they have or requesting that they provide transcripts from their high school or college.

But, how can Jodie measure people's attitudes about race? She can't look at someone and know what kind of attitude that person has, and she can't pull out a ruler, thermometer, or transcript and see how racist her subject is. Attitudes, like many psychological traits, are not visible on the surface.

Psychological measurement involves figuring out a way to assess a psychological trait. For example, Jodie might design a survey that asks people a bunch of questions about their thoughts on different things relating to racism. That is her measure.


So, Jodie has her measure, or test, for racist attitudes. But, does her survey work?

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