Study Tool: Measurement Quality Criteria (Babbie Ch. 5, Lecture 9)

Describe how the four measurement quality criteria (accuracy, reliability, validity, precision) relate to scenarios A through D. Consider which can or cannot be explained in each scenario. All four concepts will be used, though some will apply to more scenarios than others.

Scenarios:
A) A scale that is always 5 pounds off.
B) Using a scale to measure temperature.
C) A scale that gives a different weight every time.
D) A scale that tells the weight of something to the nearest hundredth of a pound.

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Definitions to keep in mind:
- precision: how concise a measure is.
- validity: the degree to which a measure reflects the underlying construct
- reliable: whether or not the same measure can be produced if the test is carried out multiple times.
- accuracy: whether or not a measure reflects reality.



Answers May Vary - Example Answers
A) Since the scale is 5 pounds off, it is not accurate. However, since it is always 5 pounds off it is reliable.
B) A scale will not give a valid measure of temperature, since scales measure weight.
C) A scale that gives a different weight ever time is not reliable, nor is it accurate.
D) A scale that gives the weight of an object to the nearest hundredth of a pound is very precise. Just because the scale is precise, we cannot assume it is also accurate, valid, or reliable.