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📏 How Reliability and Validity Work

Learn to separate consistency from correctness, test reliability across time and raters, and judge whether evidence supports a measurement claim.

3
lessons
~10 min
to learn
Adults
level
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What you’ll learn

  1. Two questions for every measureDistinguish score consistency from evidence that supports an interpretation.Reliability describes consistency or agreement; validity concerns the interpretation made from scores for a defined use and group.
  2. Find the evidenceMatch reliability and validity evidence to the measurement claim.Test–retest, inter-rater, and internal-consistency evidence answer different questions, while validity is built from several kinds of evidence.
  3. Use both ideas togetherUse reliability and validity together when choosing or interpreting a measure.Calibration and diagnostic heuristics help locate measurement problems, but the final judgment must match the construct, population, use, and evidence.

Questions this course answers

What does reliability primarily describe?

Reliability concerns stability, repeatability, or agreement in the measurement process.

Why can a reliable measure still be invalid?

Consistency does not show that the instrument measures the intended construct.

Which is an example of test-retest reliability?

Test-retest reliability examines score stability over time when the construct should be reasonably stable.

What should a validity claim include?

Validity is an evidence-based argument tied to a particular use, population, and interpretation.

Grounded in trusted sources

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Related courses

🔎Confounding: When a Third Variable Distorts an Association📝How to Avoid Plagiarism When Paraphrasing📊How Confidence Intervals Work📈Linear Regression: Read the Model📝How to Read a Rubric🧭How to Plan a Research Question🧵How to Synthesize Sources📊How to Read a Residual Plot

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