Cardiac Arrest at Day and Night. A study investigated survival rates for in-hospital patients who suffered cardiac arrest. Among 58,593 patients who had cardíac arrest during the day,...

Cardiac Arrest at Day and Night. A study investigated survival rates for in-hospital patients who suffered cardiac arrest. Among 58,593 patients who had cardíac arrest during the day, 11.604 survived and were discharged. Among 28,155 patients who suffered cardiac arrest at night, 4139 survived and were discharged (based on data from "Survival from In-Hospital Cardiac Arrest During Nights and Weekends" by Peberdy et al., Journal of the American Medical Association, Vol. 299. No. 7). We want to use a 0.01 significance level to test the claim that the survival rates are the same for day and night. In this example, use a confidence interval rather than a hypothesis test to help draw conclusions.