Indexes are composed of a combination of several variables to measure comprehensive themes such as beliefs, feelings, experiences and attitudes, that is, subjects that are difficult to answer with "yes" or "no". Developing indexes is a way to compile in a single measurement the summary of answers to questions or statements related to a single topic. There are three main steps in index development: 1. variable selection 2. analysis of the empirical relationship between these variables for the creation of the indicator 3. idex validation