WISC/WRAT COGNITIVE TEST Cognitive function was evaluated by administering portions of standardized tests to examinees aged 6-16 years at the time of the examination. This represents a variation from the usual NHANES test protocol, in which tests are conducted based on the age at the time of the household interview, rather than on the age at the time of the MEC examination. The protocol for this component did not detail any medical, safety or other exclusions. Because these tests were administered in the mobile examination center (MEC), the MEC examination sample weight (WTPFEX6) should be used for data analysis. For more information on the use of sample weights in NHANES III data analysis, refer to the NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996b). Cognitive function was evaluated using parts of two tests, the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Wide Range Achievement Test-Revised (WRAT-R). Two subtests of the WISC-R test, a verbal component (Digit Span) and a performance exam (Block Design), were administered and are considered relatively culturally unbiased (Kaufman, 1979). In addition, two subtests of the WRAT-R test, math and reading, were conducted. The WISC-R test was administered first and was followed by the WRAT-R. The scores for all four subtests used a common scale and were derived for each child relative to his/her age group based on test-specific standardization samples created by the test developers (Wechsler, 1974; Jastak, 1984; Kramer, 1995). At the time of hire, MEC interviewers were trained to conduct the WISC/WRAT examination. During annual site visits, test administration was evaluated, and re-training took place. To increase the number of evaluated examination administrations with minimum intrusion and after obtaining informed consent from the examinees or their guardians, sessions were audio-taped and reviewed for protocol adherence. Feedback was provided to the interviewers after review of the taped sessions. An automated data collection system ensured that responses obtained were within acceptable ranges. Consequently, minimal data processing and editing were required. Notes have been provided for standardized and recoded variables and for variables requiring additional explanation. Conducting only a portion of each of the WISC-R and WRAT-R tests with children in NHANES III limits data interpretation. For example, an Intelligence Quotient (IQ) cannot be calculated for an individual using the WISC-R results from NHANES III because only certain subtests were administered. The complete WISC-R examination is comprised of twelve components, six verbal and six performance modules. An IQ can be calculated only when ten of the twelve verbal and performance elements are administered. Similarly, the WRAT-R test administered in NHANES III omitted a spelling section and is, therefore, incomplete. For additional information on the tests, refer to the Manual for the Wechsler Intelligence Scale for Children-Revised (Wechsler, 1974) and the Wide Range Achievement Test-Revised Administration Manual (Jastak, 1984). WISC-R and WRAT-R test forms are not found in either the Plan and Operation of the Third National Health and Nutrition Examination Survey, 1988-94, or the test manuals. The forms are copyrighted and may be reproduced only with written permission from the publishers. Write to Jastak Associates, Inc. (1526 Gilpin Avenue, Wilmington, DE 19806) for the WRAT-R test form and to The Psychological Corporation (555 Academic Court, San Antonio, TX 78204-0952) for the WISC-R form. NHANES III Examination Data File ------------------------------------------------------------------------ WISC/WRAT COGNITIVE TEST ------------------------------------------------------------------------ RAW/STANDARDIZED/SCALED SCORES ------------------------------------------------------------------------ Positions Item description SAS name Counts and code Notes ------------------------------------------------------------------------ 4421-4423 Math raw score See note WWPMRSR 5081 000-053 286 888 Blank but applicable 25944 Blank 4424-4426 Reading raw score See note WWPRRSR 5062 000-095 305 888 Blank but applicable 25944 Blank 4427-4429 Math standardized score See note WWPMSSR 4990 046-151 91 777 Less than the lowest possible score for a particular age 286 888 Blank but applicable 25944 Blank 4430-4432 Reading standardized score See note WWPRSSR 4853 046-141 209 777 Less than the lowest possible score for a particular age 305 888 Blank but applicable 25944 Blank 4433-4434 Math scaled score See note WWPMSCSR 5081 00-20 286 88 Blank but applicable 25944 Blank 4435-4436 Reading scaled score See note WWPRSCSR 5062 00-18 305 88 Blank but applicable 25944 Blank 4437-4438 Block design scaled score See note WWPBSCSR 5036 01-19 331 88 Blank but applicable 25944 Blank NHANES III Examination Data File ------------------------------------------------------------------------ WISC/WRAT COGNITIVE TEST ------------------------------------------------------------------------ RAW/STANDARDIZED/SCALED SCORES ------------------------------------------------------------------------ Positions Item description SAS name Counts and code Notes ------------------------------------------------------------------------ 4439-4440 Digit span scaled score See note WWPDSCSR 5033 01-19 334 88 Blank but applicable 25944 Blank NHANES III Examination Data File ------------------------------------------------------------------------ WISC/WRAT COGNITIVE TEST ------------------------------------------------------------------------ GENERAL INFORMATION ------------------------------------------------------------------------ Positions Item description SAS name Counts and code Notes ------------------------------------------------------------------------ 4441 Language used in exam See note WWPLANG 206 1 Used Spanish in exam 4869 2 Used English in exam 292 8 Blank but applicable 25944 Blank 4442-4446 Examiner number WWPTECH 311 04001 316 04002 318 04003 952 04004 1744 04005 1271 04006 103 07002 9 07007 25 07014 7 07073 311 88888 Blank but applicable 25944 Blank NHANES III Examination Data File ------------------------------------------------------------------------ THIS PAGE INTENTIONALLY LEFT BLANK NOTES WWPBSCSR and WWPDSCSR: Scaled scores Scaled scores were determined using calculations provided in the WISC-R Manual (Wechsler, 1974). Refer to this publication for information on deriving these scores. Scaling scores allows comparison of WISC-R with WRAT-R test components. WWPDSCSR: Digit span scaled score See note for WWPBSCSR. WWPLANG: Language used in exam All tests were administered in either English or Spanish. Children who did not speak either language were excluded from the test, and their test results were coded as "Blank but applicable." Note that of the 292 "Blank but applicable" cases for language used in exam, 280 had all test components "Blank but applicable" (8-filled). WWPMRSR: Math raw score This variable represents the sum of the raw scores for the oral and written math tests. WWPMSCSR: Math scaled score The math scaled score (WWPMSCSR) was derived from the math raw score (WWPMRSR) using factors calculated and provided in the WRAT-R Administration Manual (Jastak, 1984). This variable represents the scaled score for the mathematics test and allows comparison between the WRAT-R and WISC-R exams. WWPMSSR and WWPRSSR: Standardized scores Standardized scores represent an age-standardized version of raw scores and were calculated according to the WRAT-R Administration Manual (Jastak, 1984). Refer to this publication for information on deriving these scores. Note that in accordance with the WRAT-R manual, the smallest standardized score possible varies by age. WWPRRSR: Reading raw score This variable represents the sum of the raw scores for the oral and formal reading tests. WWPRSCSR: Reading scaled score The reading scaled score (WWPRSCSR) was derived from the reading raw score (WWPRRSR) using factors calculated and provided in the WRAT-R Administration Manual (Jastak, 1984). This variable represents the scaled score for the reading test and allows comparison between the WRAT-R and WISC-R exams. WWPRSSR: Reading standardized score See note for WWPMSSR.