Practice Problems Module 13 (Solutions)

3. The data set “apache.txt” contains information on 30 day mortality in a sample of septic patients as a function of their baseline APACHE II Score (an integer score from 0 to 71, higher scores correspond to more severe disease). Patients are coded as 1 or 0 depending on whether they are dead or alive in 30 days, respectively. APACHE II score can be thought of as a continuous measure, but since it consists of integer values we can construct a reasonably informative table to better understand the data. Additionally, a plot and two fitted models are provided. death APACHEII 0 1 0 1 0 2 1 0 3 3 1 4 11 0 5 6 3 6 11 3 7 8 4 8 17 5 9 30 3 10 15 5 11 26 5 12 12 5 13 19 13 14 18 7 15 11 7 16 16 8 17 19 8 18 6 13 19 8 7 20 7 6 21 8 9 22 2 12 23 6 7 24 3 8 25 4 7 26 4 2 27 2 5 28 2 1 29 3 4 30 1 4 31 0 3 32 0 3 33 0 1 34 0 1 35 0 1 36 0 1 37 0 1 41 1 0 Model 1: lm(formula = death ~ APACHEII) Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) -0.002446 0.050708 -0.048 0.962 APACHEII 0.025070 0.003009 8.331 9.66e-16 *** Model 2: glm(formula = death ~ APACHEII, family = "binomial") Coefficients: Estimate Std. Error z value Pr(>|z|) (Intercept) -2.32521 0.27790 -8.367 < 2e-16 *** APACHEII 0.11673 0.01608 7.260 3.87e-13 ***