This paper introduces one item named variance rate of gray level and improves the maximum-minimum method by simplifying the noise examination process for suppressing the random impulsive noise.
Methods 696 community residents over 35 years old were selected by random cluster sampling, questionnaire, physical examination and blood glucose examination.
方法采用整群随机抽样的方法抽取696名35岁以上社区居民,开展问卷调查并进行体格检查及血糖检查。
3
The system of selecting judges at the end of Qing Dynasty went through the process from selecting based upon experience and longevity at random to selecting based upon examination.