This paper presents an analysis of user capability data using Topological Data Analysis (TDA) (unsupervised machine learning) to extract insight. The aim was to explore the global shape and sub-groupings (clusters of profiles) of people using data collected from the Cambridge Better Design Pilot Study of 362 people from across England and Wales. The resulting topological network demonstrated the global shape of the sample and distribution of sensory, cognitive and motor capability across the sample. The TDA network was automatically grouped into 14 distinct clusters, and distinguishing features of each cluster was extracted. The results demonstrate the value of applying TDA to analyse and visualise user capability data, and it is proposed that the cluster descriptions could be used for developing empirically based design tools such as personas for Inclusive Design.

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This paper presents the results of a study that specifically looks at the relationships between measured user capabilities and product demands in a sample of older and disabled users. An empirical study was conducted with 19 users performing tasks with four consumer products (a clock-radio, a mobile phone, a blender and a vacuum cleaner). The sensory, cognitive and motor capabilities of each user were measured using objective capability tests. The study yielded a rich dataset comprising capability measures, product demands, outcome measures (task times and errors), and subjective ratings of difficulty. Scatter plots were produced showing quantified product demands on user capabilities, together with subjective ratings of difficulty. The results are analysed in terms of the strength of correlations observed taking into account the limitations of the study sample. Directions for future research are also outlined.@en

Inclusive design is a user-centred approach that examines designed product features with particular attention to the functional demands they make on the perceptual, thinking and physical capabilities of diverse users, including those with impairments and ageing. An analytic approach to the evaluation of designs mitigates the need for observational trials with products by relating data about the prevalence of capability ranges in the population with an analysis of the demands made by product properties and features. This enables a quantification of the number of users who can use a specific design. To date, there has been some success in identifying data sets and appropriate impairment and capability models for perception and movement in this novel "inclusive" research context. However, previous attempts to do so for cognitive aspects of product feature interaction have encountered a lack of suitable data and models. We propose some necessary requirements for a complete model of inclusive cognitive interaction and establish four criteria for what would constitute a good framework for the purpose of developing a research approach that could be used to construct and test predictive tools for design. Taking into account the immediately relevant literature, we examine some candidate approaches that may satisfy these requirements with reference to some of our own research findings. The results of the analysis suggest that this combined approach to cognitive demand is, in principle, capable of satisfying the proposed criteria in conjunction. It has also been successful in driving a research effort to identify important predictive variables and relate these to an underlying model of interaction. The utility of such a framework will ultimately be judged by empirical tests of the accuracy of the developed model and tools in predicting specific exclusion and difficulty during cognitive interaction. This will allow further iterative improvement of the model and will also permit modification of the development framework. A further test will be whether designers can use the resulting tools to help create designs for ICT products that are more inclusive in that they are usable by people with a wider range of functional capabilities.@en

Functional capabilities in Inclusive Design may be characterised by thresholds or human performance envelopes for users with variable or reduced functional capacity. In order to validate the effectiveness of this framework, an experimental approach is reported that compared human performance and measures of perceived difficulty with actual measurements of demand for a range of products and users and with varying capability ranges. This paper explores some of the operational assumptions, for the validation study, their rationale, some quantitative results and the physical and human constraints of the test situation that had to be considered.@en

Designers require knowledge and data about users to effectively evaluate product accessibility during the early stages of design. This paper addresses this problem by setting out the sensory, cognitive and motor dimensions of user capability that are important for product interaction. The relationship between user capability and product demand is used as the underlying conceptual model for product design evaluations and for estimating the number of people potentially excluded from using a given product.@en

The inclusive design approach attempts to accommodate people with reduced functional capability as much as possible in the design of consumer products. This paper presents a generic analytical framework for the evaluation of product usability and accessibility with the aim of minimising the potential number of people excluded. This is achieved through the consideration of sensory, cognitive and motor demands placed on user populations by the design of product features. The framework is envisioned to support prediction of proportions of the user population who may be excluded or experience difficulty with a given design. The feasibility of the framework is demonstrated via a case study using a simple toaster. Though current data is lacking for making these predictions, further research is planned that will address data collection to support the analytical evaluation framework.@en

In keeping with a user capability and product demand approach to product assessment, this paper examines the cognitive demands placed on users when interacting with consumer products. The eventual aim is to develop a set of cognitive capability scales that could be used in the analytical evaluation of product interfaces. We explore the dimensions of cognitive capability relevant to product interaction and describe how these may be used to evaluate a given design. Planned work addresses quantitative measurement of cognitive capabilities and predictive validation of capability scales.

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This paper presents an analysis of the structure of the prevalence of disability and medical conditions in a representative sample of over 5000 people in the Great Britain 16- adult population. Using data from 1996/97 Great Britain Disability Follow-Up Survey, exploratory data analysis revealed the general increase in loss of ability in the older population. Summary characteristics are presented for five age groups and design implications are drawn for the practice of inclusive design.

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