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Home » Select Measures » Differences Between Measures » CAT vs. Short Form
Differences Between Measures

CAT vs. Short Form

Differences Between Measure Types

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Computer Adaptive Tests (CATs)

  • Tailored selection of items for each respondent.
  • Requires administration technology.
  • High measurement precision across a wide range of symptom/function severity.
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Short Forms

  • All respondents answer all questions.
  • No special administration technology needed.
  • Degree of measurement precision varies.
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Item Banks

  • A collection of items measuring the same domain (e.g., Anxiety).
  • Administered as a computer adaptive test (the CAT can use any item in the bank) or short form (a subset of items from the bank).
  • DO NOT administer an entire item bank to a respondent – instead use a CAT or short form.

Differences in Measurement Precision

In 2019, Segawa and colleagues compared PROMIS® CATs with 4-, 6-, and 8-item short forms. Specifically, they evaluated the range of accurate scores, number of items administered, floor (level of the worst symptom/function a measure can quantify), and ceiling (level of the best symptom/function a measure can quantify).

  • CATs offer the widest range of accurate scores.
  • CATs averaged 4.7 items administered.
  • 4-, 6-, and 8-item short forms provide a range of accurate scores that improves with longer measures. Figure 1 in their manuscript provides the specific range for each short form. This can be used to evaluate how well each short form is likely to cover the desired range of scores for a target patient sample.
  • Use CATs:
    1. “When a substantial number of participants with extremely poor health is anticipated;”
    2. “When there is a need to measure very healthy participants accurately;” and
    3. “When the administration of small number of items is required” (p. 217).

When to Use CATs

  • CATs are the preferred choice for most aims (e.g., individual patient care, research, population health).
  • CATs are ideal for individual patient care due to their reduced respondent burden and precise scores.

When to Use Short Forms

  • You require all respondents to answer the same items.
  • You do not have access to the technology needed to administer CATs (e.g., you have to use paper measures).
  • A specific short form is required by a payor or other entity (e.g., THA/TKA Global Health for CMS).

PROMIS Short Form Profiles versus CAT Profile

  • PROMIS profiles include a fixed set of measures covering a wide range of health domains. For example, the PROMIS-29 Profile is a measure for adults that includes 4-item short forms for Physical Function, Fatigue, Pain Interference, Sleep Disturbance, Depression, Anxiety, and Ability to Participate in Social Roles and Activities as well as a single Pain Intensity item.
  • Most PROMIS profile measures are constructed of short forms. However, the PROMIS Profile CAT v1.0 – 29 is constructed of CATs.
  • The CATs included in the PROMIS Profile CAT v1.0 – 29 are fixed to administer 4 items each. This is shorter than the default stopping rule for other PROMIS CATs which allows a CAT to administer a maximum of 8-12 items. The PROMIS Profile CAT v1.0 – 29 is thus fixed to administer only 29 items.
  • The PROMIS Profile CAT v1.0 – 29 is recommended over short-form based profiles because it is precise AND brief, even for asymptomatic people.
  • You can review the content of the PROMIS Profiles for adults, pediatric self-report, and parent proxy report.
  • You can also review our guidance about when to use each Profile measure. View guidance.

Last updated: September 29, 2026