Question: Preventing strokes Aspirin prevents blood from clotting and so helps prevent strokes. The Second European Stroke Prevention Study asked whether adding another anticlotting drug, named dipyridamole, would be more effective for patients who had already had a stroke. Here are the data on strokes during the two years of the study:
The study was a randomized comparative experiment.
(a) Is there convincing evidence at the a = 0.05 level that adding dipyridamole helps reduce the risk of stroke?
(b) Describe a Type I and a Type II error in this setting. Which is more serious? Explain.