Consider the regression model fit to the arsenic data in Exercise 12-16. Use arsenic in nails as the response and age, drink use, and cook use as the regressors.

(a) What proportion of total variability is explained by this model?

(b) Construct a normal probability plot of the residuals. What conclusion can you draw from this plot?

(c) Plot the residuals versus y and versus each regressor, and comment on model adequacy.

(d) Calculate Cook€™s distance for the observations in this data set. Are there any influential points in these data?

Transcribed Image Text:

Cook Arsenic Drink Arsenic Age Sex Nails Use Use Water 44 2 5 0.00087 0.119 45 4 0.00021 0.118 44 5 0.099 66 2 3 5 0.00115 0.118 0.277 37 1 45 2 5 0.358 47 1 5 5 0.00013 0.08 38 2 4 5 0.00069 0.158 0.00039 41 3 0.31 0.105 49 2 4 5 72 5 0.073 0.832 45 1 0.046 0.517 53 1 5 5 0.0194 86 5 5 0.137 2.252 8. 0.0214 0.851 32 2 5 5 0.0175 0.269 0.433 44 5 0.0764 63 5 5 0.141 0.275 42 1 5 0.0165 62 1 0.00012 0.135 0.0041 0.175 36 1