Answer to Question #155850 in Management for Prabhdeep

Question

What do you mean by reliability of a test ? is a reliable test valid too? comment while highlighting the difference (please answer in 200 to 250 words)

Answer 1

RELIABILITY OF A TEST

The reliability of test scores is the extent to which they are consistent across different occasions of testing, different editions of the test, or different raters scoring the test taker’s responses.

VALIDITY OF A RELIABLE TEST

A test can be reliable, meaning that the test-takers will get the same score no matter when or where they take it, within reason of course. But that doesn't mean that it is valid or measuring what it is supposed to measure. 

DIFFERENCE BETWEEN RELIABILITY AND VALIDITY

Reliability is about the consistency of a measure, and validity is about the accuracy of a measure.

Reliability vs validity

1. What does it tell you?

Reliability

The extent to which the results can be reproduced when the research is repeated under the same conditions.

Validity

The extent to which the results really measure what they are supposed to measure.

2. How is it assessed?

Reliability

By checking the consistency of results across time, across different observers, and across parts of the test itself.

Validity

By checking how well the results correspond to established theories and other measures of the same concept.

3. How do they relate?

Reliability

A reliable measurement is not always valid: the results might be reproducible, but they’re not necessarily correct.

Validity

A valid measurement is generally reliable: if a test produces accurate results, it should be reproducible.

Reference

Published on July 3, 2019 by Fiona Middleton

Educational Testing Service