WAIS Score Comparisons and Discrepancy Analysis 1 — Questions and Answers
Question 1: What is the primary purpose of discrepancy analysis in WAIS-IV interpretation?
- To determine whether differences between index scores are statistically significant and clinically meaningful (Correct answer)
- To calculate the examinees overall FSIQ score from raw subtest scores
- To compare the examinees scores to those of a clinical reference group only
- To identify which subtests should be excluded from composite score calculation
Correct answer: To determine whether differences between index scores are statistically significant and clinically meaningful
Discrepancy analysis examines whether differences between index or subtest scores exceed what would be expected by chance, helping clinicians identify genuine cognitive strengths and weaknesses.
Question 2: In WAIS-IV tables, what two criteria are used together to determine whether a pairwise index score discrepancy is clinically significant?
- Statistical significance (critical value) and base rate (frequency in the standardization sample) (Correct answer)
- Raw score difference and age-corrected standard score difference
- Effect size (Cohen's d) and confidence interval overlap
- Standard error of measurement and practice effect estimate
Correct answer: Statistical significance (critical value) and base rate (frequency in the standardization sample)
A discrepancy must first exceed the critical value (statistical significance) and then be evaluated against base rate tables to determine how unusual that difference is in the normative population.
Question 3: A clinician notes that an examinee's VCI is 108 and WMI is 88. The critical value at p < .05 is 11 points. What is the correct interpretation?
- The 20-point discrepancy is statistically significant, but base rate data are needed to judge clinical meaningfulness (Correct answer)
- The discrepancy is not significant because neither score falls in the impaired range
- The discrepancy is clinically significant because both scores differ by more than one standard deviation
- No interpretation is possible without the Processing Speed Index score
Correct answer: The 20-point discrepancy is statistically significant, but base rate data are needed to judge clinical meaningfulness
Because 20 points exceeds the critical value of 11, the difference is statistically significant; the clinician must then consult base rate tables to determine how commonly such a difference occurs in the normative sample.
Question 4: What does the 'base rate' refer to in WAIS-IV discrepancy analysis?
- The percentage of individuals in the standardization sample who showed a discrepancy of a given size or larger (Correct answer)
- The average score difference expected between any two index scores in the general population
- The minimum score difference required for a finding to reach statistical significance
- The reliability coefficient of the index score being compared
Correct answer: The percentage of individuals in the standardization sample who showed a discrepancy of a given size or larger
Base rate data indicate how frequently a particular discrepancy occurs in the normative sample, helping clinicians decide whether a statistically significant difference is also clinically unusual.
Question 5: Which WAIS-IV index score comparison is most sensitive to detecting the effects of acquired brain injury affecting frontal-executive functions alongside processing speed?
- Processing Speed Index (PSI) compared to Verbal Comprehension Index (VCI) (Correct answer)
- Working Memory Index (WMI) compared to Perceptual Reasoning Index (PRI)
- Full Scale IQ compared to General Ability Index (GAI)
- Verbal Comprehension Index (VCI) compared to Working Memory Index (WMI)
Correct answer: Processing Speed Index (PSI) compared to Verbal Comprehension Index (VCI)
PSI versus VCI comparisons are especially sensitive to acquired neurological conditions because PSI tasks are highly vulnerable to brain injury while VCI, reflecting crystallized knowledge, often remains more intact.
Question 6: When comparing an examinee's individual subtest scaled scores to their own mean scaled score, this approach is called:
- Ipsative or person-centered comparison (Correct answer)
- Normative or criterion-referenced comparison
- Age-corrected z-score comparison
- Interrater reliability analysis
Correct answer: Ipsative or person-centered comparison
Ipsative (intraindividual) comparison evaluates each subtest relative to the examinee's own average, revealing relative personal strengths and weaknesses independent of normative standing.
Question 7: A significant VCI > PRI discrepancy in a right-handed adult is most consistent with which neuropsychological hypothesis?
- Relative weakness in right-hemisphere visuospatial processing compared to left-hemisphere verbal abilities (Correct answer)
- Generalized intellectual decline affecting all cognitive domains equally
- Preferential impairment of phonological processing and reading decoding
- Elevated crystallized intelligence relative to working memory capacity
Correct answer: Relative weakness in right-hemisphere visuospatial processing compared to left-hemisphere verbal abilities
Because PRI tasks rely heavily on right-hemisphere visuospatial processing, a VCI > PRI pattern in a right-handed individual can suggest relative right-hemisphere dysfunction.
WAIS Score Comparisons and Discrepancy Analysis 1
What is the primary purpose of discrepancy analysis in WAIS-IV interpretation?