Patients with coronary artery disease were randomly assigned to either receive angioplasty plus medical therapy (n = 1149) or medical therapy alone (n = 1138) in a clinical trial. Over the next several years 85 angioplasty and 95 medical therapy patients died, with cause of death categorized as cardiac, other, or unknown. The following table shows a cross classification of the data. Is there statistically significant evidence, at the 0.10 level, to conclude that there is an association between treatment group (angioplasty versus medical therapy) and outcome?
(a) State the null and alternative hypotheses in context.
(b) How many degrees of freedom are there for a chi-square test?
(c) The P-value for the chi-square test is 0.87 If α = 0.10, what is your conclusion regarding H0?

Transcribed Image Text:

Unknown Angioplasty Medical therapy Total Cardiac death Other death cause of death Alive Total 1,064 1.149 1.043 1138 2.107 2,287 23 25 48 45 51 96 17 19 36