Methods To collect data by cluster sampling and analyze data by polychotomous Logistic regression.

法采用整群抽调查搜集资料,采用多类回归析筛选影响因素。

Indicate epidemiology investigation , confirm on the grounds of international sampling investigation, major part in the cancerogenic patient who has a smoke is a passive smoker.

流行病学调查表明，据国际性的抽调查证实，吸烟致癌患者中的大是被动吸烟者。