How to Measure Disability

There are various ways in which surveys help us to measure how common disability is. Here, we summarise the key recommendations for measuring disability in research:

The Washington Group Enhanced Short Set (WGES)

The Washington Group tools are the most commonly used world-wide, so using them allows comparison with other settings and over time. The WGES includes questions on mental health and upper body function, which increase the proportion of people with disabilities identified compared with the Short Set. See Step 2.2 for a review of shorter two-question tools that can be used where insufficient resources exist to embed the WGES, but remember the challenges with this approach.

Supplementing the WGES With Other Tools

If your research is related to health or rehabilitation services, or has a focus on people with particular impairments, it may be useful to include impairment tools and/or clinicians in your research. Remember that clinical impairment tools may require more resources, and that impairments are not a proxy for disability.

Boy with bilateral cataract having vision assessed before intervention in Nepal. Image copyright: CBM

Use Established Definitions

It is important to follow guidance on how to interpret your raw data to measure disability: i.e. to use established analytical thresholds and approaches. You should also present data that are disaggregated by age group, sex, type of functional limitation and socio-economic position, given that we know there are differences in disability prevalence and impact in these different groups.

Have Sufficient Resources in Place

Self-reported tools must be accurately translated (if using the Washington Group tools, check the Washington Group website to see if a translation already exists), and data collection teams must be well trained on how to deliver the questionnaires and record the responses. Tools must be appropriate for the context that you are working in. Use mobile tools where feasible, to avoid data entry errors or data being misplaced. If using clinical tools make sure that these are in good working order, well-calibrated and used in a standardised way by a trained individual, following a protocol.

Measuring Disability in Context

Finally, remember that there is no “one size fits all” when it comes to measuring disability in research. Use methods that are appropriate to the context, to your research question and to the resources at your disposal. Research and pilot test tools before beginning your data collection, and follow available guidance and best practice in generating thresholds and interpreting results.