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While working with doctors on heart attack patients, we want to predict whether

ID: 3365328 • Letter: W

Question

While working with doctors on heart attack patients, we want to predict whether the patient will have a second heart attack within 1 year (yes = 1), based on two predictor variables: whether the patient completed an anger-control treatment course (yes=1), and the patient's score on a trait anxiety scale (a higher score means more anxious). Data on 20 patients is used to fit the following logistic regression:

What probability of second heart attack does the equation predict for someone who has NOT taken the anger treatment course and whose anxiety level is 50?

Predictor Coef SE Coef Z P Constant -6.36347 3.21390 -1.98 0.048 AngerTrt -1.02411 1.17108 -0.87 0.382 Anxiety 0.119045 0.0549790 2.17 0.030

Explanation / Answer

Formula: Logit(P) = -6.36347 -1.02411*AngerTrt + 0.119045*Anxiety

P = 1/[1+exp(-(-6.36347 -1.02411*AngerTrt + 0.119045*Anxiety))]

P = 1/[1+exp(-(-6.36347 - 1.02411*0 + 0.119045*50))] = 1/[1+exp(0.41122)] = 0.3986 = 39.86%(Option A)