Question

Each year, more than 1 million heart patients undergo an angioplasty. The benefits of an angioplasty were challenged in a recent study of 2,287 patients (2007 Annual Conference of the American College of Cardiology, New Orleans). All the patients had substantial blockage of the arteries but were medically stable. All were treated with medication such as aspirin and beta-blockers. However, half the patients were randomly assigned to get an angioplasty and half were not. After five years the researchers found that 211 of the 1,145 patients in the angioplasty group has subsequent heart attacks, compared with 202 of 1,142 patients in the medication-only group. Conduct a hypothesis test to determine, at the 0.05 level of significance, whether getting an angioplasty decreases the risk of subsequent heart attacks.

please show steps on TI-84 Plus CE and write your conclusion in words

Answer 1

Using TI-84 Plus:

Press [STAT] -> "TESTS" ->"2-PropZTest"

and enter the data as below.

Choose "Calculate" and Press [ENTER]. The results appears as below.

We see the P-value of the left-sided Z-test is . Hence we cannot reject the null hypothesis. The conclusion is

"We are 95% confident that getting an angioplasty does not decrease the risk of subsequent heart attacks"

The P-value plotted below.