Refer to Data Set 7 “IQ and Lead” in Appendix B and find the best regression equation with IQ FULL (full IQ score) as the response (y) variable. Use predictor variables of IQ VERB (verbal IQ score) and IQ PERF (performance IQ score). Why is this equation best? Based on these results, can we predict someone’s full IQ score if we know their verbal IQ score and their performance IQ score? Is such a prediction likely to be very accurate?

Refer to the indicated data set in Appendix B and use technology to obtain results.

Data Set 7: IQ and Lead 

Data are from 121 subjects (first five rows shown here). Data are measured from children in two consecutive years, and the children were living close to a lead smelter. LEAD is blood lead level group [1 = low lead level (blood lead levels < 40 micrograms/100 mL in both years), 2 = medium lead level (blood lead levels ≥ 40 micrograms/100 mL in exactly one of two years), 3 = high lead level (blood lead level ≥ 40 micrograms/100 mL in both years)]. AGE is age in years, SEX is sex of subject (1 = male; 2 = female). YEAR1 is blood lead level in first year, and YEAR2 is blood lead level in second year. IQ VERB is measured verbal IQ score. IQ PERF is measured performance IQ score. IQ FULL is measured full IQ score.

Data are from “Neuropsychological Dysfunction in Children with Chronic Low-Level Lead Absorption,” by P. J. Landrigan, R. H. Whitworth, R. W. Baloh, N. W. Staehling, W. F Barthel, and B. F. Rosenblum, Lancet, Vol. 1, No. 7909.