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. (3) Calculate the t statistic for each slope. From the pvalues, which slopes differ from zero at a = .01? (Round your answers to 2 decimal places. Negative values should be indicated by a minus sign.) Es time ted Std Dependent Variable R2 Slope Error tcalculated pValue Differ from 0? Highest grade achieved 0 . 062 70 . 038 0 . 010 . 000 (Click to select) v Reading grade equivalent 0 . 159 0 . 100 0 . 034 . 004 (Click to select) v Class standing 0.021 0.005 0.028 .859 (Click to select) V Absence from school 0.055 3.000 1.610 .065 (Click to select) v Grammatical reasoning 0.061 0.133 0.053 .013 (Click to select) v Vocabulary 0.115 0.203 0.021 .000 (Click to select) v Handseye coordination 0 . 02'?II 0 . 044 0 . 025 . 081 (Click to select) v Reaction time 0.031 10.300 3.100 .001 (Click to select) v Minor antisocial behavior 0.034 0.617 0.637 .335 (Click to select) V (b) It would be inappropriate to assume cause and effect without a better understanding of how the study was conducted