Reading focus
Syllabus: How Do We Know What a Psychological Test Measures?
Trace the route from a construct definition to an item pool, validation samples, and decisions about what to retain.
Why you’re reading it. See how design choices can strengthen or compromise a measurement claim before the main study begins.
A question to consider. What should the Persistence Scale include—and exclude—to distinguish sustained effort from having abundant time and resources?
Why this reading
Scale construction begins with a defensible account of the attribute and its boundaries. Clark and Watson connect that account to item selection, sampling, dimensional structure, and evidence that a proposed measure adds something useful.
Before you read
An item pool is the set of candidate questions. A factor represents shared variation under a statistical model. Unidimensionality concerns one underlying dimension; internal consistency concerns relationships among items. They are not interchangeable.
Read for
- Follow how the definition determines which content belongs in the initial item pool.
- Ask why closely related constructs and heterogeneous validation samples matter.
- Distinguish improving a coefficient from improving coverage of the intended attribute.
Consider afterwards
- A shorter questionnaire has more similar items but loses an important aspect of a construct. What evidence would justify keeping or rejecting it?
Editorial context
This updates the authors’ 1995 paper, with an emphasis on language-based instruments relevant to clinical assessment. Its recommendations require judgment about constructs and populations; they do not constitute a universal mechanical recipe for every kind of measure.