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Computer Adaptive Tests (CATs)

Computer Adaptive Tests (CATs) 

Computer Adaptive Tests (CATs) are a type of measure in which the questions a person answers are tailored to that person. Each response is used to further refine a person’s score.

Item Banks
All CATs begin from an item bank.

  • Item bank = collection of items (questions) all measuring the same thing (e.g., physical function)
  • Items are ordered by level of difficulty/severity from low (e.g., I have difficulty getting in and out of bed) to high (I am able to run 5 miles) using Item Response Theory

Tailoring Items to a Respondent

  1. The first item administered in a CAT is usually one in the middle of the range of function or symptom severity.
  2. After a person provides a response, an estimated score is calculated.
  3. The CAT algorithm then selects the best item in the item bank for refining the estimated score.
  4. After a person provides a response, the estimated score is recalculated.
  5. The CAT continues to administer items until:
  • A specified level of measurement precision is reached (e.g., <3.0 on a T-score metric) OR
  • A specified maximum number of items was administered (generally 12 for HealthMeasures)

Why use CATs?

  • Brief - Usually 4-12 items; can be completed in under a minute
  • Precise - Low error
  • Tailored content - CATs don’t ask questions that aren’t relevant to the respondent
  • Cover a wide range of function or symptoms

Interested in using PROMIS Computer Adaptive Tests (CATs)?

Try the PROMIS CAT Demo>>

Learn more about CATs

  • For a visual explanation of CAT, please see part 6 of Karon Cook’s video series “Applications of IRT".

 

PROMIS CAT Stopping Rules

Adults

  • Minimum number of items administered = 4
  • Stop when one of these occurs:
    • 12 items are administered OR
    • The standard error is below a threshold (0.3 on the theta metric or 3.0 on the T-score metric)

Pediatrics and Parent Proxy

  • Minimum number of items administered = 5
  • Stop when one of these occurs:
    • 12 items are administered OR
    • The standard error is below a threshold (0.4 on the theta metric or 4.0 on the T-score metric)