17. A clinical trial is run to assess the efficacy of a new pacemaker device in patients with atrial fibrillation (AF). Two hundred participants are randomized to receive the new pacemaker or a...

17. A clinical trial is run to assess the efficacy of a new pacemaker device in patients with atrial fibrillation (AF). Two hundred participants are randomized to receive the new pacemaker or a currently available pacemaker. There are two primary outcomes of interest: the number of days in a 3-month period with an atrial fibrillation event, and hospitalization for atrial fibrillation over the 3-month follow-up period. Data on baseline characteristics and the outcomes are shown in
Table 6–28.

TABLE 6–28 Baseline Characteristics of Participants in Pacemaker Study

Compute a 95% confidence interval for the difference in mean number of days with an AF event between participants receiving the new pacemaker as compared to the available pacemaker.

Compute a 95% confidence interval for the mean number of days with an AF event among participants receiving the new pacemaker.

18. A clinical trial is run comparing a new drug for high cholesterol to a placebo. A total of 40 participants are randomized (with equal assignment to treatments) to receive either the new drug or placebo. Their total serum cholesterol levels are measured after eight weeks on the assigned treatment. Participants receiving the new drug reported a mean total serum cholesterol level of 209.5 (SD = 21.6) and participants receiving the placebo reported a mean total serum cholesterol level of 228.1 (SD = 19.7).

Construct a 95% confidence interval for the difference in mean total serum cholesterol levels between participants receiving the new drug versus placebo.

s the new drug effective? Justify briefly.