Reading focus
Syllabus: How Do We Know What a Psychological Test Measures?
Compare the proposed causal requirement with Messick’s account of justified interpretations and uses.
Why you’re reading it. Understand a substantive disagreement about the target of validation, rather than treating validity as an agreed checklist.
A question to consider. If family resources explain both scale responses and course completion, what would the causal account require before calling this a measure of persistence?
Why this reading
The authors propose that measurement requires an existing attribute whose variation causes variation in test outcomes. This makes validity a claim about a measurement process and distinguishes it from useful prediction or a persuasive interpretation.
Before you read
Ontology concerns what exists; epistemology concerns how we know. A causal account asks how an attribute produces a response. A predictor can forecast something without measuring the attribute named in its label.
Read for
- Separate the proposed definition of validity from the evidence needed to establish it.
- Ask why correlations among tests cannot, by themselves, identify the response-generating process.
- Follow the distinction between validity as a property and validation as an investigative activity.
Consider afterwards
- A questionnaire predicts exam results. What evidence would show that it measures persistence rather than prior knowledge or available study time?
Editorial context
The causal account is a philosophical and methodological proposal, not a settled resolution of validity theory. Compare it with Messick’s broader account. Excluding social consequences from a definition of measurement does not remove the need to evaluate test use.