Every design decision has the potential to include or exclude customers. Inclusive design emphasizes the contribution that understanding user diversity makes to informing these decisions, and thus to including as many people as possible. User diversity covers variation in capabilities, needs and aspirations.
This page first presents an example set of 'Product performance indicators', i.e. things that should be considered when thinking about how well a product or service is performing. It discusses how users' needs fit into this set. It then explains how delivering breakthrough advances across the whole set of performance indicators requires understanding diversity within the population and responding to this diversity through Inclusive design. Comparisons with 'Design for all' and 'Universal design' are also presented.
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Inclusive design focuses on the diversity of people and the impact of this on design decisions. However, the complete set of performance indicators should consider a wider set of aspects concerned with People, Profit and Planet, as described in the 'Performance indicator framework' diagram shown opposite.
The performance indicators should examine how the different aspects have an impact across the whole life-cycle of the product. This life-cycle typically involves the stages:
- Develop it
- Make it
- Distribute & sell it
- Use it
- Pass it on
- Reprocess it
For most current products, the user 'Passes it on' by throwing it in the bin, and 'Reprocess it' involves storage in landfill. However, recycling and refurbishment represent other alternatives for these stages.
Failure to correctly understand people can result in products that cause unnecessary frustration and exclusion, which reduces commercial success because of increased returns and customer support.
In order to better understand population diversity, it is important to challenge the polarised separation of 'able-bodied' and 'disabled'. Research commissioned by Microsoft (2003) to investigate the benefit of accessible technology makes the following comment:
The concept of "disability" may have limited the understanding of the need for accessible technology ... the IT industry must consider the wide range of people who could benefit. '
Diversity within the population is better modelled using a pyramid to model the full range of ability variation within a population. This pyramid can then be segmented to identify various categories of users. The bottom segment of the pyramid represents those with no difficulties, and the severity of difficulties increases up the pyramid. A specific interpretation of this pyramid model is shown opposite.
Population diversity has been introduced first from the perspective of ability variation, but can be further broadened to consider diversity associated with different real-world contexts, lifestyle, aspirations, gender, and past experiences. In summary, 'it's normal to be different' (Lange and Becerra, 2007).
- A report by Microsoft (2003): 'The Wide Range of Abilities and its Impact on Computer Technology' presents survey results on the range of abilities in the US population and discusses the current and potential market for accessible technology.
- A paper by Lange and Becerra (2007): 'Teaching universal design in Colombia: the academic approach of two universities' discusses perceptions of disability and explains how it is 'normal to be different'. Published in the Include 2007 Conference Proceedings.
The British Standards Institute (2005) defines inclusive design as:
'The design of mainstream products and/or services that are accessible to, and usable by, as many people as reasonably possible ... without the need for special adaptation or specialised design.'
Inclusive design does not suggest that it is always possible (or appropriate) to design one product to address the needs of the entire population. Instead, inclusive design guides an appropriate design response to diversity in the population through:
- Developing a family of products and derivatives to provide the best possible coverage of the population.
- Ensuring that each individual product has clear and distinct target users.
- Reducing the level of ability required to use each product, in order to improve the user experience for a broad range of customers, in a variety of situations.
See the Case studies section for commercially successful examples of inclusive design.
The British Standards Institute (2005) standard BS 7000-6:2005: 'Design management systems - Managing inclusive design - Guide' defines inclusive design and provides guidance on managing it. It can be purchased from the BSI website.
'Design for all' and 'Universal design' philosophies both have the same literal meaning. These philosophies originated from design of the built environment and websites, and were initially applied in the context of government provision (Design for All Foundation; Preiser and Ostroff, 2001).
In the context of product design, both 'Design for all' and 'Universal design' approaches pragmatically accept that it is not always possible for one product to meet the needs of the entire population. Nevertheless, these approaches maintain that all mainstream products should be accessible to as many people as technically possible (Preiser and Ostroff, 2001).
In contrast, inclusive design originated with product design, and focuses on choosing an appropriate target market for a particular design, and making informed decisions to maximise the 'Product performance indicators' for that target market. While inclusive design intends to extend the reach of mainstream products, it acknowledges the commercial constraints associated with satisfying the needs of the target market.
For websites and the built environment, the target population is generally the whole population, in which case all three approaches have an equivalent meaning.
- The website of the Design for All Foundation provides more information about 'Design for all'.
- Preiser and Smith (2001)'s book: 'Universal Design Handbook' gives more information about universal design. (Published by McGraw-Hill, New York, USA).
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