Question

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 t statistic for each slope. From the p-values, which slopes differ from zero at α = .01? (Round your answers to 2 decimal places. Negative values should be indicated by a minus sign.)

  

Dependent Variable	R2	Estimated Slope	Std Error	tcalculated	p-value	Differ from 0?
Highest grade achieved	0.099	-0.022	0.018		0.224	(Click to select)YesNo
Reading grade equivalent	0.135	-0.056	0.013		0.000	(Click to select)NoYes
Class standing	0.012	-0.002	0.011		0.856	(Click to select)NoYes
Absence from school	0.079	5.000	1.220		0.000	(Click to select)YesNo
Grammatical reasoning	0.035	0.164	0.030		0.000	(Click to select)YesNo
Vocabulary	0.150	-0.289	0.047		0.000	(Click to select)NoYes
Hand-eye coordination	0.051	0.021	0.018		0.246	(Click to select)YesNo
Reaction time	0.024	11.500	3.810		0.003	(Click to select)YesNo
Minor antisocial behavior	0.015	-0.851	0.482		0.080	(Click to select)YesNo

   

(b)	It would be inappropriate to assume cause and effect without a better understanding of how the study was conducted.

Answer 1

a)

here as test statsitic t=estimated slope/std error

Dependent Variable	R2	Estimated Slope	Std Error	tcalculated	p-value	Differ from 0?
Highest grade achieved	0.099	-0.022	0.018	-1.22	0.224	No
Reading grade equivalent	0.135	-0.056	0.013	-4.31	0.000	Yes
Class standing	0.012	-0.002	0.011	-0.18	0.856	No
Absence from school	0.079	5	1.22	4.10	0.000	Yes
Grammatical reasoning	0.035	0.164	0.03	5.47	0.000	Yes
Vocabulary	0.150	-0.289	0.047	-6.15	0.000	Yes
Hand-eye coordination	0.051	0.021	0.018	1.17	0.246	No
Reaction time	0.024	11.5	3.81	3.02	0.003	Yes
Minor antisocial behavior	0.015	-0.851	0.482	-1.77	0.080	No

b)

true