The Pattern Language Network

Taming web2.0 in Higher Education

Posts Tagged ‘Validity’

An inconvenient thesis?

Posted by yishaym on October 7, 2008

Christine Elizabeth Wania’s phd thesis questions the empirical evidence for the benefits of pattern languages in HCI:

For more than two decades much of the pattern language literature, within the field of Human Computer Interaction (HCI), has focused on the possible benefits pattern languages may provide, but there has been very little empirical work to support these claims. It has been suggested that interaction patterns or pattern languages in HCI may address some of the problems inherent in designing interactive systems by supporting reuse, capturing design knowledge, enabling the sharing of design knowledge, and facilitating communication among designers and users. This study examined the impact of a pattern language on the design of information retrieval interfaces, in terms of the quality of the interfaces and the time to design the interfaces. Participants created paper and pencil interfaces based on the given design task. Participants were exposed to either a pattern language, guidelines, or no structuring technique. There were no statistically significant differences between the three groups in terms of the quality of the interfaces and time to design the interfaces. The results of this study suggest that the value of pattern languages in HCI may not be in reuse, at the early stages of design, or in terms of the quality of the resulting designs, in domains familiar to designers. Although there was no apparent impact of the pattern language on the early stage designs, the results of a follow-up study suggest there is a significant correlation between the existence of patterns in commercial systems and the overall usability of those systems. Therefore, we suggest that we, as a community, very closely examine the current state of pattern languages in HCI before continuing to move forward. As a community, we need to shift our focus away from discussing the possible benefits of pattern languages and trying to build pattern collections. And instead, focus on trying to fully understand the value of pattern languages in HCI. In doing so, the HCI community, will then begin to see the benefits from all the great efforts in this area.

About time someone asked this question. I mean, I’ll swear by my favourite patterns and pattern languages, defend them as if they where my children flesh and blood, but do we have any evidence, in the scientific sense? In a way, this brings back the discussion on validity, resonance and aggregation. Yes, patterns work great for those who believe in them. But shouldn’t we aim higher?

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Validity, Resonance and Aggregation

Posted by yishaym on August 21, 2008

I’ve been chatting with Christian Kohls of Knowledge Media Research Center about pattern languages, workshops, community engagement, and the big picture. The discussion brought up some issues which where floating around EuroPLoP, and resonated with recent discussions on the Liberating Voices mailing list (pss – the book is out).

I see three major challenges pattern language communities to address:


What’s the scientific process of showing that a pattern does what it claims? Is it science, or is it art? What kind of evidence does a pattern need? How can we get the scientific community to accept patterns as a valid tool of knowledge production?

Even looking at Christopher Alexander’s patterns, the question arises. Alexander has a “confidence” measure, but what is it based on?


In the Learning Patterns project, we noted:

Paradoxically, often as more expert knowledge is embedded in a pattern language it becomes less accessible to novices. The Learning Patterns project has tried to address this issue by a small set of Trails which accompany our pattern language.

But perhaps the problem goes deeper. Again and again, at every workshop we run, we see how hard it is for people to “get into the pattern groove”. Primarily, patterns are about abstraction without loosing context – and I think that is precisely what most people find hard. No wonder patterns have caught on so well in software engineering communities. After all, abstraction in context is what software engineers are trained to do.

So how do we break out of the cosy cult of patternisers, and make the knowledge we accumulated accessible to the wider public?


Once there was one pattern language for architecture (Alexander’s). Then there was one for software (GoF). Now there’s hundreds. Spread all over the place. Patterns are supposed to capture the essence of a recuring problem and its tried and tested method of solution. But they are supposed to capture it ONCE. In a way that can be referenced, linked, composed into larger structures or decomposed into sub-elements. What we’re seeing now is a fragmentation which defies the core purpose of the project.

How do we avoid reinventing wheels? How do we make sure that we build on each others’ work as much as possible, and aggregate design knowledge systematically?

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