Assessment Design

Validity

25 min

Simple Explanation

Validity is the extent to which an assessment measures what it claims to measure. It is the single most important quality criterion — without validity, assessment results are meaningless.

Professional Definition

Validity is the degree to which evidence and theory support the interpretation of assessment scores for proposed uses. It is a unitary concept with multiple forms of evidence: content, construct, criterion, and consequential validity.

Explain It to a 10-Year-Old

If a driving test only had a written section about cars and never made you actually drive, would it be a valid driving test? No — because it does not measure driving ability. That is validity.

Why It Matters

Invalid assessment has real consequences: learners receive qualifications without real competence, employers trust credentials that do not represent ability, and regulators may withdraw recognition.

Where It Fits in the Process

This topic belongs to Assessment Design in the assessment development journey.

Assessment Strategy Assessment Methods Blueprint Question Writing Validity Reliability

Step-by-Step Process

1

Define the construct

What exactly is being measured?

2

Check content coverage

Does the assessment cover all criteria?

3

Verify method alignment

Does the method validly assess the construct?

4

Review for irrelevant variance

What might affect scores that is not the construct?

5

Build an evidence argument

Document why the assessment is valid

Worked Example

Valid: A practical spreadsheet task to assess spreadsheet skills. The learner must actually use software.
Invalid: An MCQ about spreadsheet features to assess spreadsheet skills. The learner may know about spreadsheets but cannot use them.
The first directly measures the construct; the second measures knowledge about the construct.

Common Mistakes

Mistake	Problem	Better Approach
Assuming a test is valid because it is published	Publication does not guarantee validity	Build and document the validity argument
Confusing reliability with validity	Reliable does not equal valid. You can reliably measure the wrong thing	Check construct alignment before worrying about consistency

Checklist

All criteria covered?
No gaps in assessment coverage

Methods aligned to constructs?
Practical skills assessed practically

Irrelevant barriers removed?
Accessibility, bias, language checked

Validity argument documented?
Can you explain why this assessment is valid?

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Related Tool

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Interview Connection

You may be asked about this topic in assessment developer interviews.

Practice Interview Questions

Knowledge Check (3 Questions)

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Summary

Validity = does the assessment measure what it claims to?
Validity is not binary — it is a continuum requiring evidence
Content validity: does it cover all required content?
Construct validity: does it measure the right underlying ability?
Consequential validity: are the outcomes fair and appropriate?