A study was based on the records of 6789 patients in 369 hospitals in which the patients’ hearts stopped because of conditions that could have been reversed by an electrical shock from a defibrillator. The percentages of patients who survived at least until being discharged from the hospital are shown in Table 27 for various delays in the hospital staff giving the shock.
Table 27 Delays in Using Defibrillator versus Percentages of Patients Who Survived
Delay (minutes)Percent
1………………………………..39
2………………………………..38
3………………………………..34
4………………………………..23
5………………………………..25
6………………………………..18
7………………………………..14
Let p be the percentage of patients who survived a delay of d minutes before receiving treatment from a defibrillator.
a. Construct a scatterplot.
b. Is there a linear association, a nonlinear association, or no association?
c. Compute r. On the basis of the scatterplot and r, describe the strength of the association.
d. Expert guidelines say the shock should be given within 2 minutes after the heart stops. Explain why this cutoff makes sense.
e. Hospital staffs took longer than 2 minutes for 30% of their patients. Estimate the number of patients in the study who died in the hospital due to the delay being more than 2 minutes. To simplify the calculations, assume that all delays more than 2 minutes took 4 minutes.