tate whether the investigation in question is an observational study or a designed experiment. Justify youranswer in each case. Heart Failure. In the paper “Cardiac-Resynchronization Therapy with or without an Implantable Debrillator in Advanced Chronic Heart Failure” (New England Journal of Medicine, Vol. 350, pp. 2140–2150), M. Bristow et al. reported the results of a study of methods for treating patients who had advanced heart failure due to ischemic or nonischemic cardiomyopathies. A total of 1520 patients were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy alone or in combination with either a pacemaker or a pacemaker–debrillator combination. The patients werethen observed until they died or were hospitalized for any cause.
tate whether the investigation in question is an observational study or a designed experiment. Justify your
answer in each case.
Heart Failure. In the paper “Cardiac-Resynchronization Therapy with or without an Implantable Debrillator in Advanced Chronic Heart Failure” (New England Journal of Medicine, Vol. 350, pp. 2140–2150), M. Bristow et al. reported the results of a study of methods for treating patients who had advanced heart failure due to ischemic or nonischemic cardiomyopathies. A total of 1520 patients were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy alone or in combination with either a pacemaker or a pacemaker–debrillator combination. The patients were
then observed until they died or were hospitalized for any cause.
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