CASSM project

The history of CASSM

CASSM was conceived on a bus, somewhere in southern Norway, in the summer of '95. We (Thomas and Ann) were comparing notes about our experiences of usability evaluation. In particular, we both felt frustrated about the poor take-up of theoretically grounded techniques. At the time, Thomas was working on ERMIA and Ann on PUM (look elsewhere for references!) - both of which seemed to have some really strong features, but were clearly too difficult for rapid take-up. Conversely, Thomas' work on Cognitive Dimensions was being picked up and used by other people ... but CDs only told part of the story, and even that relatively informally. What we wanted was a simple approach that was more rigorous than CDs but easier to learn and use than ERMIA or PUM. So UUUM (Usable, Useful, Used Modelling) was born.

Subsequent conversations in pubs in Cambridge and Sheffield refined the idea into OSM (Ontological Sketch Modelling) - capturing the ontology of the user's and the system's model in a sketchy way. On the third attempt, we obtained funding from EPSRC to develop and test the approach, and Iain Connell joined us. As we refined the representation (or ontology!) of OSM, we started to develop tool support, in the form of OSMosis. And that tool, in turn, helped us to understand better what it was we were trying to do.

The focus of the work shifted towards identifying misfits between users, interfaces and systems. We also realised that there were two important classes if misfits: surface ones, where there is a simple mismatch between the concepts the user is working with and those implemented in the system, and structural misfits, which emerge in the ways the user can interact with (and change) the structure of a representation. So, once again, we changed the name and also the design of the support tool. CASSM (Concept-based Analysis of Surface and Structural Misfits) is now supported by the Cassata tool. And we believe we have largely achieved what we originally set out to do: to deliver a modelling approach that is useful and usable; only time will tell how much it is used.

The final report to EPSRC on the funded project gives a reasonable summary of the funded work and its outcomes.

This page last modified 26 February, 2010 by Ann Blandford