III. >> M  ethodological Approaches to Human Rights Indicators >> Disaggregation of human rights indicators that evolve over time. The collection of data for additional characteristics of the population will usually have cost implications. Producing disaggregated data that are collected through statistical surveys will tend to widen confidence intervals (see glossary) if the size of the samples of the targeted groups does not increase, which entails further data collection. The publication, analysis and exploitation of data at a lower level of aggregation will demand additional resources.51 tivity of asking ethnicity questions. The same source provides a broad definition of ethnicity: ethnicity is based on a shared understanding of history and territorial origins (regional and national) of an ethnic group or community, as well as on particular cultural characteristics such as language and/or religion. Respondents’ understanding or views about ethnicity, awareness of their family background, the number of generations they have spent in a country, and the length of time since immigration are all possible factors affecting the reporting of ethnicity in a census. Ethnicity is multidimensional and is more a process than a static concept, and so ethnic classification should be treated with movable boundaries. Disaggregation of data by religion or ethnicity could also be politically and socially difficult when used wrongly. When fictitious numbers (either through inflating or deflating data) are produced to serve a political purpose, it could create divisions among people. On the other hand, disaggregated data could be used so that minorities and other population groups are made more visible so as to provide evidence for targeted policymaking and help their integration. Proponents of the inclusion of questions on ethnicity and religion in census and survey questionnaires have also observed that respondents have the option of replying to these questions or not. However, it may not always be enough to just include this option in the questionnaire. Interviewers may have to clearly explain and reiterate this option to the respondents. In relation to human rights and disaggregating data on the basis of disability, for instance, the Convention on the Rights of Persons with Disabilities is clearer on disaggregation and requires States: to collect appropriate information, including statistical and research data, to enable them to formulate and implement policies to give effect to the present Convention. … The information collected … shall be disaggregated, as appropriate, and used to help assess the implementation of States Parties’ obligations under the present Convention and to identify and address the barriers faced by persons with disabilities in exercising their rights (art. 31). There is no blanket human rights obligation for a country to disaggregate statistical information by ethnic characteristics or other potentially sensitive data. In relation to ethnicity, for instance, the Principles and Recommendations for Population and Housing Censuses stipulate that the decision to collect disaggregated data is dependent upon a number of considerations and national circumstances, including, for example, the national needs for such data, and the suitability and sensi- Generally, international human rights bodies have encouraged the disaggregation of data on the basis of the prohibited grounds of discrimination. A non-exhaustive list of these grounds includes: sex, age, economic and social situation, race, colour, language, religion, political or other opinion, national or social origin, property, birth, disability, health status, nationality, marital and family status, sexual orientation and gender identity, place of residence, and other status. 51. Discussions between users of statistical data, including national human rights bodies, and data producers, as part of the work of OHCHR on human rights indicators with national statistical offices and other local organizations, have highlighted the underuse of already collected data. Human Rights Indicators 69