Simple regression was employed to establish the effects of childhood exposure to lead. The effective sample size was about 122 subjects. The independent variable was the level of dentin lead (parts per million). Below are regressions using various dependent variables. (a) Calculate the rstatistic for each slope, at significance level = 0.01. (Negative values should be indicated by a minus sign. Round your answers to 2 decimal places.) R2 Differ from 0? Yes Yes No Yes Dependent Variable Highest grade achieved Estimated Slope Std. Error tcalculated p-value e.e09 .061 -0.027 .008 Reading grade equivalent Class standing Absence from school .121 -0.070 e.e18 .e0e .039 -0.006 e.003 .048 .071 4.8 1.7 .006 Grammatical reasoning Vocabulary Hand-eye coordination .051 0.159 e.062 .012 No 0.032 .000 Yes No .108 -.124 .043 0.041 e.018 .020 Reaction time 6.66 No No .025 11.8 .080 Minor antisocial behavior .025 -.639 0.36 .082 (b) It would be inappropriate to assume cause and effect without a better understanding of how the study was conducted.