Reliability Vs Validity

Table of Contents

Reliability and validity are two important concepts in research that are used to evaluate the quality of measurement instruments or research studies.

Reliability

Reliability refers to the degree to which a measurement instrument or research study produces consistent and stable results over time, across different observers or raters, or under different conditions.

In other words, reliability is the extent to which a measurement instrument or research study produces results that are free from random error. A reliable measurement instrument or research study should produce similar results each time it is used or conducted, regardless of who is using it or conducting it.

Validity

Validity, on the other hand, refers to the degree to which a measurement instrument or research study accurately measures what it is supposed to measure or tests what it is supposed to test.

In other words, validity is the extent to which a measurement instrument or research study measures or tests what it claims to measure or test. A valid measurement instrument or research study should produce results that accurately reflect the concept or construct being measured or tested.

Difference Between Reliability Vs Validity

Here’s a comparison table that highlights the differences between reliability and validity:

	Reliability	Validity
Definition	The degree to which a measurement instrument or research study produces consistent and stable results over time, across different observers or raters, or under different conditions.	The degree to which a measurement instrument or research study accurately measures what it is supposed to measure or tests what it is supposed to test.
Concerned with	Consistency and stability of results	Accuracy and truthfulness of results
Types	Test-retest reliability, inter-rater reliability, internal consistency reliability	Content validity, criterion validity, construct validity
Measure	Degree of agreement or correlation between repeated measures or observers	Degree of association between a measure and an external criterion, or degree to which a measure assesses the intended construct
Example	A bathroom scale that consistently provides the same weight measurement when used multiple times in a row	A math test that measures only the math skills it is intended to test and not other factors, such as test-taking anxiety or language ability.