Why Include The WG Questions On Both Surveys And The Census?

Why include the Washington Group (WG) questions on a census, if they are included in the survey infrastructure of a country?  Most indicators for the Sustainable Development Goals (SDGs) come from household surveys. These include household income and expenditure surveys, demographic and health surveys, labor force surveys, UNICEF’s multiple indicator cluster survey, etc. To disaggregate SDG indicators by disability status, as explained in a different blog entry , a country simply has to add the WG questions to existing surveys.  If this is done, why then take up potentially expensive space on a census form to also include the WG questions there? What is gained from including the WG questions on a census that can’t be obtained from household surveys?

There are several reasons to include the WG questions on a census:

• Geographic patterns: The prevalence of disability is influenced by many factors that can vary geographically. Only a census can enable a country to identify regions with high rates of disability that can help isolate the causes of disability. In the diagram below, from a Vietnam census, you can see how much these rates can vary^[1].