The Washington Group short set (WG-SS) questions are increasingly integrated into national household surveys, censuses, and international survey programs. They enable the monitoring of disability rights and the production of internationally comparable statistics. Disability statistics on prevalence and inequalities can be estimated using different cut-offs on the degree of functional difficulties based on the WG-SS. This commentary discusses what cut-offs to adopt for the purpose of investigating and monitoring disability gaps. We recommend a three-way disaggregation comparing persons with (a) no difficulty, (b) some difficulty and (c) a lot of difficulty or unable to do. In cases where sample sizes are small for disaggregated analysis, we recommend comparing persons with no difficulty to persons with any level of difficulty (i.e. persons with any disability).