CASSM project

A set of examples

On this page we describe examples of analysing real systems using CASSM.

Each example includes a very brief description of of the system with references to a published full description; what misfits the CASSM analysis revealed, with links to our published and unpublished papers; and the actual CASSM model in 3 forms, of which the first (html) is a full version, the second (.jpg) is a screenshot from Cassata, and the third (.csm) is a text file that can downloaded and input into Cassata if wished.

1. Tallis, a knowledge representation tool
2. Two ticket vending machines
3. A drawing application
4. A digital music library
5. An intranet system

Tallis

Tallis (Cancer Research UK) is a knowledge representation tool to support clinical diagnosis and treatment. The output from Tallis Composer is a guideline which can be run on a remote server using Tallis Enactor.

The Tallis study was important for two reasons. Firstly, it involved the CASSM developers working directly within an ongoing design context, to explore the use of CASSM within design practice. Secondly, the study enabled us to distinguish between different kinds of users: in this case, the guideline developers ("composers") and the guideline users ("consumers"). The system developers ("creators") have to design directly for the composers, and less directly for the consumers.

We are in the process of writing up this work, and the paper will appear here soon(ish).

Tallis Composer:

CASSM model: (a) html (b) screenshot from Cassata (c) .csm output

Tallis Enactor:

CASSM model: (a) html (b) screenshot from Cassata (c) .csm output

Fox, J., Beveridge, M. and Glasspool, D. (2003). Understanding intelligent agents: analysis and synthesis. AI Communications, 2003, vol 16, pp 139-152.

Fox, J., Johns, N. and Rahmanzadeh, A. (1998). Disseminating medical knowledge: the PROforma approach. Artificial Intelligence in Medicine, 1998, vol 14, pp 157-181.

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Ticket vending machines

All London Underground stations have at least one of each of two types of ticket machine, namely the FFM (Few Fare Machine) and the larger MFM (Multi-Fare Machine). The FFM has remained largely unchanged since installation in the late 1980s; the MFM's original hard button array was replaced in 2000-2001 by a touch screen interface. This analysis concerns the MFM (and FFM) interface as it was in Autumn 2002.

This workenabled us to compare data from user observations and interviews against a CASSM analysis and also a Cognitive Walkthrough analysis, as part of the exercise of scoping CASSM. See Connell et al (2004).

CASSM model: (a) html (b) screenshot from Cassata (c) .csm output

Connell, I.W. (1998). Error analysis of ticket vending machines: comparing analytic and empirical data. Ergonomics, 1998, vol 41, no. 7, pp 927-961.

Connell, I.W., Blandford, A.E. and Green, T.R.G. (2004). CASSM and Cognitive Walkthrough: usability issues with ticket vending machines. Behaviour & Information Technology, 2004, vol. 23, no. 5, pp 307-320.

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Drawing Application

A typical desktop drawing tool application allows users to create and manipulate vector graphics, and combine edited components into a finished drawing. Drawing objects (rectangles, lines, polygons, etc.) are typically available on palettes or toolbars, along with additional editing functions (group, rotate, join, etc.).

Drawing tools were probably the most pivotal systems in our early thinking about CASSM (when it was called OSM), because it seemed to us that having a good understanding of the underlying concepts and their relationships was much more important in understanding how a drawing tool might be used than having any understanding of task structures, at anything higher than a trivial level of description. See Connell et al. (2003).

CASSM model: (a) html (b) screenshot from Cassata (c) .csm output

Connell, I.W., Green, T.R.G. and Blandford, A.E. (2003). Ontological Sketch Models: highlighting user-system misfits. In E. O'Neill, P. Palanque and P. Johnson (eds.), People and Computers XVII - Designing for Society. Proceedings of HCI 2003, Bath, September 2003, pp. 163-178. London: Springer

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A digital music library

The New Zealand Digital Library consists of around 30 sub-collections, one of which is the Music Library. The Music Library allows users to search for, query, download and play back melody files stored in various formats on a remote server.

The analysis was based on interviews with several music specialists, and highlighted some important user difficulties with the system of the time. Note that the system has been completely redesigned since our analysis (partly informed by it). An outline of the analysis is included in Connell et al. (2003).

CASSM model: (a) html (b) screenshot from Cassata (c) .csm output

Bainbridge, D. (2000). The role of Music IR in the New Zealand Digital Library project. In: International Symposium on Music Information Retrieval (ISMIR), Plymouth, Mass., October 2000.

McNab, R.J., Smith, L.A., Bainbridge, D. and Witten, I.H. (1997). The New Zealand Digital Library MELody inDEX. In: D-Lib Magazine, May 1997.

Witten, I. H., Bainbridge, D. & Boddie, S. J (2001). Greenstone: Open-source digital library software with end-user collection building. Online Information Review, vol 25, no. 5, pp 288-298.

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An intranet system

The Whittington is a UK National Health Service teaching hospital serving part of North London. This analysis concerns the Whittington staff Intranet.

For reasons explained by Connell and Blandford (undated), this study was more difficult and less immediately insightful than anticipated. However, completing it forced us to reflect on the importan differences between "designerly" and view-only systems – by which we mean the difference between systems where users can change the structure of information in some meaningful way and those for which they cannot. This led to the insight about surface and structural misfits, and a name change from OSM to CASSM.

CASSM model: (a) html (b) screenshot from Cassata (c) .csm output

Darmoni, S.J. and Thirion, B. (1998), Internet and Intranet Web Sites at Rouen University Hospital. http://www.chu-rouen.fr/dsii/html/interdefeng.html

Hatcher, M. (2001), Intranet usage and potential in acute care hospitals in the United States: survey -2000. International Journal of Medical Systems, 2001, vol 25, no 6, pp 345-355.

Ong, K.R. (2001), Building and growing a hospital intranet: a case study. Journal of Medical Internet Research, 2001, vol 3, no 1, e10.

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Further analyses will be added here, just as soon as we can find the time to put them into a suitably presentable format.

This page last modified 26 February, 2010 by Ann Blandford