The basic principle of the Dependability Model of Domestic Systems is that it considers dependability within the context of both the domestic environment and the user. We adapt Jean-Claude Laprie et al's model of dependability, which is used for software development, into a more social method for analysing the dependability of domestic AT systems. Essentially we agree with Laprie et al that there were four branches to dependability within domestic contexts namely 'acceptability', 'trustworthiness', 'adaptability' and 'fitness for purpose'. These attribute are displayed and interact differently to the way these attribute would within a software context.

Technology is required to be acceptable, if it is not it is rejected;
It needs to be trustworthy, (when I turn this knob this happens every time), if not it will be rejected;
It needs to be adaptable, (I can use this in this room as well as in this room) and most importantly
It must be 'fit for purpose' (This device is going to assist me to do this therefore it must do X, Y, and Z under A, B and C circumstances), if not it will be rejected. The diagram below is our initial attempt to represent these design issues.

These attributes are mediated through the home context and the interactions with the user.

 

 

This model shows only part of the story. If we conceptualise the design to that of assistive devices or systems we can see that the home actually becomes the defining factor. How people interact with, and within, their living space is critical. Their interactions with technology are mediated through their activities within these domestic spaces. In other words, what we do in the home effects how we use things,and therefore needs to be reflected in the design of assistive systems. Similarly the environment places limits on the technology usage and limits what technology can be used and how it can be used. The structure of the domestic space can also affect the technology use and design criteria substantially. If a person has difficulty walking around their home because the design of the spaces makes it difficult for the person then adding technology will not alleviate the difficulty but merely compound it. If spaces are limiting they should be redesigned before introducing technology.

It is therefore possible to see that the original four branches are actually containing a number of other elements that effect the dependability of the system for the user. These elements can be considered within a user context as well as a system context. The diagram below acts a a two dimensional representation of the social model. As with all models by characterising them in a linear form of visualisation one is missing the interactivity between the elements. The four branches are not there to contain the elements and the diagram should be seen as a dynamic process with aspects of each element moving from branch to brach.

Clearly, this model shows only part of the story. If we conceptualise the design to that of assistive devices or systems we can see that the home actually becomes the defining factor. How people interact with, and within, their living space is critical. Their interactions with technology are mediated through their activities within these domestic spaces. In other words, what we do in the home effects how we use things and therefore needs to be reflected in the design of assistive systems.

Inevitably, new things will come on to the market that we cannot base a accurate judgment on as we possibly do not know that much about the new device. Through using the dependability framework, we can begin to see things that we should question about this new device. Arming oneself with a good list of questions allow us to develop a better picture of the overall design, as well as clarifying the minutiae which can often be the most costly and time consuming parts of a design. The questions allow the design to become overt and the framework can be used as a means of explaining and talking through critical elements of the design with other people who might not have your own skills or expertise.

It is with these issues on board that I began to develop MDDS. MDDS is a tool for assessing devices and people's needs in relation to potential technology design. It is a means of specifying but does not produce a blanket solution, instead it provides a means of building up a number of questions that are important to the design in relation to the system and the people who will use it. DTA is a tool for assisting telecare assessments.

See also the dirc page here and the Design pages