Inequity is the presence of systematic and potentially remediable differences among population groups defined socially, economically, or geographically [1,2]. It is not the same as inequality, which is a much broader term, generally used in the human rights field to describe differences among individuals, some of which are not remediable (at least with current knowledge). Some languages do not make a distinction between the two terms, which may lead to confusion and a need to clarify exact meaning in different contexts. Some people use the term "unfairness" to define inequity, but unfairness is not measurable and therefore not a useful term for policy or evaluation. Inequity can be horizontal or vertical. Horizontal inequity indicates that people with the same needs do not have access to the same resources. Vertical inequity exists when people with greater needs are not provided with greater resources. In population surveys, similar use of services across...