[概念] 属性抽样(attribute sampling)和变量抽样(variable sampling)

PMBOK(2004 3rd 英) P191中提到了质量控制中要注意区分的几个概念，其中提到了属性抽样与变量抽样这一对概念，书上没有详细解释，查阅如下：

Attribute Sampling (http://www.answers.com/topic/attribute-sampling?cat=biz-fin) :

Statistical procedure used to study the characteristics of a population. Attribute is a qualitative characteristic that a unit of a population either possesses or does not possess. For example, an account receivable is either past due or not; proper authorization for a payment either exists or does not. Thus the population under consideration is composed of two mutually exclusive classes-units possessing the attribute and units not possessing it. The statistical procedure used to estimate the occurrence of a particular attribute in a population is referred to as attribute sampling.

Attribute sampling is particularly valuable in estimating the extent of compliance, such as the effectiveness of accounting controls using tests of transactions. Tables are used to determine sample size based on the desired confidence level, upper precision limit, and the expected rate of occurrence.

Variable Sampling: (在google搜索框中输入define:Variable sampling查询到的结果)

A sampling technique used to estimate the average or total value of a population based on a sample; a statistical model used to project a quantitative characteristic, such as a dollar amount.