53. There is a great deal of geographical variation in the frequency of many surgical procedures-up to tenfold varition per hundred thousand people among different areas in the numbers of hysterectomies, prostatectomies, and tonsillectomies. To support a conclusion that much of the varition is due to unnecessary surgical procedures, it would be most important to establish which of the following? (B) The varition is unrelated to factor (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered. 請問一下原題的意思是?? 答案B，為什麼跟這些考慮要動手術的因素無關呢??? OV詳解看不太懂 麻煩大家了 謝謝!! --

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