The following portion of an abstract gives information on the comparison of treatments of men with prostate cancer. Read it and answer the questions about it below. The prostate gland surrounds the neck of the bladder in men. "Methods: Between 1989 and 1999, we randomly assigned 695 men with early prostate cancer to watchful waiting or radical prostatectomy and followed them through the end of 2012. The primary end points in the Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4) were death from any cause, death from prostate cancer, and the risk of metastases.
a. Compare the percentages of death for the two groups descriptively.
Which group had patients who were more likely to live?
b. Find and compare the percentage who died from prostate cancer for each group.
c. Was this an observational study or a controlled experiment?