Definitions for quality domains.

*The categories of ‘inadequate’ and ‘unclear’ were collapsed to create a binary variable for each quality domain for use in the logistic regression: ‘adequate (1)’ versus ‘inadequate or unclear (0)’.将‘不合格（inadequate）’与‘不明确（unclear）’两个类别归并，为每个质量维度（quality domain）构建用于逻辑回归（logistic regression）的二分类变量，该变量的类别划分标准为‘合格（1）’与‘不合格或不明确（0）’。