There is a great deal of geographical variation in the frequency of many surgical procedures-up to tenfold variation per hundred thousand people among different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies.
To support a conclusion that much of the variation is due to unnecessary surgical procedures, it would be most important to establish which of the following?
【选项】The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered.
To support a conclusion that much of the variation is due to unnecessary surgical procedures, it would be most important to establish which of the following?
【选项】The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered.
