WAIS FSIQ and GAI Interpretation 2 — Questions and Answers
Question 1: When a clinician calculates the GAI instead of the FSIQ, which two index scores are intentionally excluded?
- VCI and PRI
- WMI and PSI (Correct answer)
- VCI and WMI
- PRI and PSI
Correct answer: WMI and PSI
The GAI is derived from the VCI and PRI only, deliberately omitting Working Memory Index and Processing Speed Index scores.
Question 2: A GAI that is significantly higher than the FSIQ most commonly suggests that the examinee has relative weaknesses in:
- Verbal comprehension and fluid reasoning
- Working memory and processing speed (Correct answer)
- Visual-spatial and fluid reasoning
- Verbal comprehension and working memory
Correct answer: Working memory and processing speed
When GAI > FSIQ by a meaningful amount, it indicates that working memory and/or processing speed are dragging the full-scale score down.
Question 3: On the WAIS-IV, what is the lowest possible FSIQ score that can be reported?
- 40 (Correct answer)
- 45
- 50
- 55
Correct answer: 40
The WAIS-IV FSIQ has a floor of 40, meaning scores below 40 are not reliably differentiated by the test.
Question 4: Which statistical concept explains why a very high or very low FSIQ score is likely to be closer to the population mean upon retesting?
- Standard error of measurement
- Regression to the mean (Correct answer)
- Practice effect
- Ceiling effect
Correct answer: Regression to the mean
Regression to the mean describes the statistical tendency for extreme scores to move closer to the population average on re-examination.
Question 5: A clinician interprets an FSIQ of 85 as falling in the 'Low Average' classification. What percentile rank does this score correspond to approximately?
- 5th percentile
- 10th percentile
- 16th percentile (Correct answer)
- 25th percentile
Correct answer: 16th percentile
An FSIQ of 85 is one standard deviation below the mean of 100 and corresponds to approximately the 16th percentile.
Question 6: For the GAI to be considered a valid and interpretable composite, the VCI and PRI subtests must first meet what condition?
- Both indexes must be above 90
- The discrepancy between VCI and PRI must not be too large (Correct answer)
- All subtests must have scaled scores above 7
- The examinee must complete testing in a single session
Correct answer: The discrepancy between VCI and PRI must not be too large
A large and statistically significant discrepancy between VCI and PRI reduces the meaningfulness of the GAI as a unitary composite.
Question 7: Which of the following best describes the 'base rate' consideration when interpreting an FSIQ–GAI discrepancy?
- The frequency of that discrepancy in the general population (Correct answer)
- The reliability coefficient of the FSIQ
- The test-retest stability of the GAI over six months
- The standard error of prediction for future academic performance
Correct answer: The frequency of that discrepancy in the general population
Base rate refers to how often a given FSIQ–GAI discrepancy size occurs in the normative sample, which helps determine clinical significance.
WAIS FSIQ and GAI Interpretation 2
When a clinician calculates the GAI instead of the FSIQ, which two index scores are intentionally excluded?