Wechsler Psychometric Properties Questions and Answers 1 — Questions and Answers
Question 1: The Full Scale IQ (FSIQ) of the WAIS-IV has an average internal consistency reliability coefficient of .98. What does this high coefficient primarily indicate?
- The test accurately predicts future academic performance.
- The test items consistently measure the same underlying construct. (Correct answer)
- The test scores are stable over a six-month period.
- The test is free from cultural bias across all populations.
Correct answer: The test items consistently measure the same underlying construct.
Internal consistency reliability (often measured by Cronbach's alpha or split-half reliability) refers to the degree to which different items on a test that propose to measure the same general construct produce similar scores. [5] A high coefficient like .98 indicates that the items are highly interrelated and consistently measuring the same thing (in this case, general intellectual ability). [3, 5]
Question 2: A school psychologist finds that a student's WISC-V FSIQ score is highly correlated with their scores on a nationally standardized achievement test administered during the same week. This finding provides strong evidence for the WISC-V's:
- Test-retest reliability
- Content validity
- Internal consistency
- Concurrent validity (Correct answer)
Correct answer: Concurrent validity
Concurrent validity, a form of criterion-related validity, is demonstrated when scores from a test are significantly correlated with scores from a relevant, established measure administered at approximately the same time. The strong correlation between the WISC-V (an intelligence test) and an achievement test supports the idea that the WISC-V is measuring cognitive abilities related to current academic performance. [24, 33]
Question 3: An examiner calculates a 95% confidence interval of [104, 116] for an examinee's Verbal Comprehension Index (VCI) score of 110. The width of this interval is directly determined by the:
- Examinee's motivation level during testing.
- Standard error of measurement (SEM) for the VCI. (Correct answer)
- Size and representativeness of the normative sample.
- Flynn effect observed in the population.
Correct answer: Standard error of measurement (SEM) for the VCI.
A confidence interval is constructed around an obtained score to estimate the range within which the individual's 'true' score likely falls. This range is calculated using the standard error of measurement (SEM), which quantifies the amount of error inherent in any test score. A larger SEM results in a wider confidence interval, and a smaller SEM results in a narrower one. [4, 8, 10]
Question 4: Which of the following is the most critical feature of the standardization sample used to develop the norms for a Wechsler intelligence scale?
- It must be limited to individuals from a specific geographic region to control for cultural differences.
- It must include a minimum of 10,000 participants to ensure statistical power.
- It must be representative of the general population on key demographic variables. (Correct answer)
- It must be composed entirely of individuals with diagnosed learning disabilities.
Correct answer: It must be representative of the general population on key demographic variables.
The primary goal of a standardization sample is to be representative of the population for whom the test is intended. This is achieved by stratifying the sample based on key demographic variables like age, sex, race/ethnicity, geographic region, and parent education level, matching recent census data. [21, 27, 28] This representativeness allows for meaningful comparison of an individual's score to their peers.
Question 5: Test developers regularly update and re-standardize the Wechsler scales. A primary psychometric reason for this is to counteract the 'Flynn effect,' which refers to the observed phenomenon of:
- The rising scores of the population on intelligence tests over generations. (Correct answer)
- A decrease in test-retest reliability over time.
- The increasing correlation between verbal and non-verbal subtests.
- A reduction in the standard deviation of scores in the normative sample.
Correct answer: The rising scores of the population on intelligence tests over generations.
The Flynn effect is the well-documented, long-term trend of rising scores on intelligence tests in many parts of the world. [1, 2, 9] To ensure that an IQ score of 100 continues to represent the average performance of the current population, tests must be periodically re-normed on a new, contemporary standardization sample. Using outdated norms would result in artificially inflated scores. [14]
Question 6: When interpreting a significant discrepancy between two index scores (e.g., VCI and PSI), it is crucial for a clinician to consider the base rate of that difference in the normative sample. Why is consulting base rate information essential for sound interpretation?
- It proves that the observed score difference is the direct cause of the referral concern.
- It determines the 95% confidence interval around each index score.
- It confirms the examiner administered the subtests in the correct order.
- It indicates how frequently that specific score difference occurred in the general population. (Correct answer)
Correct answer: It indicates how frequently that specific score difference occurred in the general population.
Base rates provide information on how frequently a particular score difference occurred in the standardization sample. A difference that is statistically significant might still be relatively common in the general population. Consulting base rates helps the clinician determine if the discrepancy is not just statistically significant but also clinically unusual or rare, which is critical for forming accurate diagnostic hypotheses. [6, 12, 32]
Wechsler Psychometric Properties Questions and Answers 1
The Full Scale IQ (FSIQ) of the WAIS-IV has an average internal consistency reliability coefficient of .98.
What does this high coefficient primarily indicate?