Question

Problem 07-19 Algo (Categorical Independent Variables)

A recent 10-year study conducted by a research team at the Great Falls Medical School was conducted to assess how age, systolic blood pressure, and smoking relate to the risk of strokes. Assume that the following data are from a portion of this study. Risk is interpreted as the probability (times 100) that the patient will have a stroke over the next 10-year period. For the smoking variable, define a dummy variable with 1 indicating a smoker and 0 indicating a nonsmoker.

Risk	Age	Systolic Blood Pressure	Smoker
10	58	152	Yes
25	65	163	No
12	58	155	No
57	86	177	Yes
28	59	196	Yes
50	76	189	Yes
17	56	155	Yes
32	78	120	No
37	80	135	No
15	78	98	No
22	71	152	No
36	70	173	Yes
15	67	135	Yes
48	77	209	Yes
15	60	199	No
36	82	119	Yes
8	66	166	No
34	80	125	No
4	62	117	No
38	59	209	Yes

(a)

Develop an estimated multiple regression equation that relates risk of a stroke to the person's age, systolic blood pressure, and whether the person is a smoker.

Let x₁ represent the person's age.

Let x₂ represent the person's systolic blood pressure.

Let x₃ represent whether the person is a smoker.

If required, round your answers to three decimal places. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank

b)	Is smoking a significant factor in the risk of a stroke? Explain. Use a 0.05 level of significance.

(c)

What is the probability of a stroke over the next 10 years for Art Speen, a 67-year-old smoker who has a systolic blood pressure of 175?

What action might the physician recommend for this patient?

d)

An insurance company will only sell its Select policy to people for whom the probability of a stroke in the next ten years is less than .01. If a smoker with a systolic blood pressure of 230 applies for a Select policy, under what condition will the company sell him the policy if it adheres to this standard?

e)

What other factors could be included in the model as independent variables? Choose the correct answer below.

(i)	Family History of Stroke
(ii)	Weight/obesity
(iii)	Gender
(iv)	All of the above

Answer 1