Wechsler Preschool and Primary Scale of Intelligence - 3rd Edition

Purpose:  Designed to measure intellectual abilities and academic achievement.

Population:  Children, aged 2:6 years through 7:3 years.

Scales: Verbal, Performance, Full Scale IQS, Processing Speed Quotient, and General Language Composite

Time:  30-35 minutes for children aged 2:6-3:11 and 40-50 minutes for ages 4-7:11.

Author:  David Wechsler

Publisher:  The Psychological Corporation

Description: The Wechsler Preschool and Primary Scale of Intelligence - Third Edition is a revision of the WPPSI-R and has extended the age range, updated the norms, added new subtests and composite scores, and claims to have a developmentally appropriate structure based on contemporary intelligence and cognitive development theory.  The artwork has been updated, and some the test material has been made more child-friendly and engaging.  Some modifications in the administration and scoring make the scales easier to use.

Scoring:  The WPPSI-III contains 4 core subtests for ages 2:6 to 3:11; Receptive Vocabulary, Information, (VIQ) Block Design, Object Assembly (PIQ), and 7 for ages 4:0 to 7:3; Information, Vocabulary, Word Reasoning (VIQ), Block Design, Matrix Reasoning, Picture Concepts (PIQ), and Coding (FSIQ). Supplemental tests for 2:6 to 3:11 group are Picture naming and Receptive Vocabulary (GLC). For the 4 to 7:3 group the supplementary tests are Symbol Search, Comprehension, Picture Completion, Similarities, Object Assembly (PSQ), and the optional subtests are Receptive Vocabulary and Picture Naming (GLC).  The WPPSI-III employs the Deviation IQ (M=100, SD=15) for the Verbal, Performance and Full Scale IQS, and scaled scores (M=100, SD=3) for the subtests

Reliability:  The reliability coefficient of the WPPSI-III subtests range from .83 to .95.  The reliability coefficients for the composite scales ranged from .89 to .96.  Test-retest reliabilities for a mean interval of 26 days for the 2:6 to 3:11 year old group Verbal, Performance, Full and General Language scores were .90, .84, .92 and .92 respectively.  For the 4 to 7:3 year old group for Verbal, Performance, Processing Speed, Full and General Language werer.92, .87, .93, .92, and .90 respectively.

Validity:  The evidence of previous research that because of the similarity of content, much of the research on the validity of the WPPSI- R The scores derived from the WPPSI-R correlate well with the WPPSI, WISC-R, Stanford Binet (4th ed.), and McCarthy Scales (rs between WPPSI-R FSIQs and other test composites range from .74 to .90). The correlation between the WPPSI-R FSIQ and the Kaufman-Assessment Battery for Children (K-ABC) Mental Processing Composite is low (.49), but the K-ABC has consistently yielded lower correlations with other intelligence tests as well. These results imply good criterion validity for the WPPSI-R. There are also studies showing the discriminant validity of the WPPSI-R with gifted, mentally deficient, learning disabled, and speech-language impaired children.

Norms:  The normative sample included 1700 children in nine age groups. The sample was representative of the US population of children aged 2:6 to 7:3 for sex, race/ethnicity, parental education level and geographic region.

Suggested use:  The WPPSI-III for assessment of general intellectual functioning as part of an assessment to identify giftedness, delays, or mental retardation.  Results can be useful in guiding clinical or school related placements.