In a study of saliva cotinine, seven subjects, all of whom had abstained from smoking for a week, were asked to smoke a single cigarette. The cotinine levels at 12 and 24 hours after smoking are provided in Table E8.2.
(a) Draw a scatter diagram to show a possible association between the cotinine levels (24-hour measurement as the dependent variable) and check to see if a linear model is justified.
Cotinine Level (mmol/L)
|
Subject
|
After 12 hours
|
After 24 hours
|
|
1
|
73
|
24
|
|
2
|
58
|
27
|
|
3
|
67
|
49
|
|
4
|
93
|
59
|
|
5
|
33
|
0
|
|
6
|
18
|
11
|
|
7
|
147
|
43
|
(b) Estimate the regression parameters, the 24-hour measurement for a subject with a 12-hour cotinine level of 60 mmol/L, and draw the regression line on the same graph with the scatter diagram.
(c) Test to see if the two cotinine levels are independent; state your hypotheses and choice of test size.
(d) Calculate the coefficient of determination and provide your interpretation.