The Exclusion Calculator: A Demographics-Based Approach to Design
- Exclusion
Who does this case study involve?
The Engineering Design Centre, University of Cambridge
The case
This study concerns the redevelopment of an exclusion calculator, a software tool that provides designers with a realistic appreciation of the number of people with disabilities that will be excluded, depending on their design choices. The exclusion calculator is generally used as part of an exclusion audit, based on the principle that an individual is excluded from using a product if their capabilities are less than the abilities demanded by the product, given the environmental context. For example, if a mobile telephone has small buttons requiring a certain level of dexterity to use them, then a user with low dexterity capability may be unable to use the device correctly, particularly depending on environmental conditions, such as cold weather.
The exclusion calculator is based on a dataset from the UK Disability Follow-up Survey (DFS), and participants in that survey were asked up to 300 questions about their ability to perform a range of everyday tasks, such as reading newspaper print and picking up small items. Their answers were then grouped into 13 ability categories, seven of which are most relevant for product design: “Seeing‟, “Hearing‟, “Intellectual Function‟, “Communication‟, “Locomotion‟, “Reach & Stretch‟, and “Dexterity‟. Additionally, each activity was given a “severity score”, since different tasks have a different level of impact on an individual’s quality of life.
The original version of the exclusion calculator only considered the activity aspects of the survey, however, there is additional answers that was incorporated into the redesign of the exclusion calculator which better determined the impact of each individual’s capabilities on quality of their life. These new answers also allowed the redesign to further refine the seven categories above into subscales in each category, which researchers called “demand types”. The main experiment in this research examined the division of capabilities into these demand types, and, in particular, it investigated whether participants are able to consistently determine the demand type of a given task, within the context of an exclusion audit. Forty people took part in the experiment, 20 men and 20 women, aged between 20 and 60.
Findings
The participants were able to accurately and consistently determine the demand type of a given activity with a high level of accuracy, therefore these are good data points to use in the exclusion calculator. It is also worth mentioning that although the exclusion calculator is focused on measuring a single task, it is possible to measure the exclusion in an entire task sequence, such as making a phone call, by using the same exclusion calculator and treating this as a sequence of tasks, and therefore, setting the demand for each capability to the maximum demand for that capability over the whole set of tasks.
It is worth noting that this type of calculator can be used to promote inclusion, but can also be used to make judgments as to how many people an organization is happy to exclude for a given cost/benefit analysis scenario, and it is also worth noting that such tools only consider individual capabilities rather than how communities can support each other in doing their tasks. Thus, tools like these are helpful as part of a design process, but should not replace designers working directly with individuals with disabilities as part of a co-design process.
References
Goodman-Deane, J., Waller, S., Williams, E., Langdon, P. and Clarkson, J. (2011) “Estimating exclusion: a tool to help designers”. Session 1A–Civic and Social, p.107.