Flow Diagrams

by on October 25, 2004

For the past couple of weeks, I have been doing flow diagrams in Visio. These are supposed to describe the “flow” of pages that a user goes through when ordering certain things on our client’s site. They are exhaustive representations of every permutation of that journey, showing the exceptions, error screens, diversions, etc. that are encountered. And sweet Jesus are they boring to do. Not only that, but they’re frustrating, confusing, relentless and needlessly time-consuming. Let me count the ways…

I don’t hate flow diagrams – I just think they’re not a good use of time. They also fail the clarity test (the user has to work out what “language” they are in before they can “read” them in order to understand what they say). This is pretty similar to my dislike of site maps, actually.

The main problem in constructing them is that you have to apply ridiculous amounts of brain power to get them laid out on the page – even to express the simplest of things. Not only that, but when you need to accommodate a change (since we’re both discovering how things work as well as recommending changes here) you have to throw it all up in the air and re-jig the thing.

They also make it too easy to be vague. For example, we had a review meeting for some diagrams today, and somebody asked about a step marked with an arrow going into it, but with no arrow coming back to the previous step (which they expected). The box in questions was a pop-up window to a third party site, from where there is no explicit link back to the main journey. So what do the arrows mean, exactly? I dunno – that you go there, and er, then maybe come back. Well, they said, I should annotate that then. Yeah, I thought, well I want to write it all down, actually, and then we wouldn’t be having this stupid conversation about what arrows mean….

I did at first suggest that we simply do them as text and maybe produce flow diagrams once the text descriptions were stable, but it seems the client’s used to diagrams. I would have been able to produce clearer, more accurate (and certainly far easier to read) descriptions of the flows in text in literally half the time it’s taken me to wrestle them to the ground with Visio. And this is on a project where everyone’s complaining about lack of time.

The only thing about flow diagrams that might be better than text is that you can jump in to part of the flow and start looking at it from there without having to read the preceding text to get to that point. But you can do that too with proper use of text formatting (highlighting names of pages, for example). And compare that to the many, many advantages of text and, well, I’ve made my point.

But I will stick with it for now so as not to rock the boat. I’m gonna try harder to get people to see the value of text next time though, and that’s for sure. If I get time, I’ll post some examples by way of a comparison to show you what I mean.

— some days later —

Here’s an A/B comparison. It’s not a very good example since both are pretty ropey. They’re not my work (I’m to busy to think up examples, dammit!), but if I’d written the textual example I’d have done it differently. It’s in the right ball park though. Similarly with the flow diagram. They both say roughly the same thing (the text has more business logic in it – Hmm, funny that), so compare one and contrast the other.

The text version would take next to no time to type up and would be a synch to edit, leaving you more time to think about the logic. Meanwhile, the flow diagram would sap your will to live and leave you no time to think about whether it was complete, would be understood, or even made sense.


Visual shorthand
I was chatting to somebody about this the other day, and they agreed. They also pointed out that while pictures are good at describing things, they’re not good at describing concepts. That’s basically it in a nutshell: draw a picture of a tree, and everyone on the planet will recognise it as a tree. Draw a picture of jurisprudence and you’re not going to get very far.

Yet we’d both heard people talking about creating a “visual shorthand” to explain a concept. This stuck us as doubly odd since that’s what words are, aren’t they? A pretty powerful visual shorthand refined over a couple of thousand years in fact. Hard to top that on an aggressive deadline.

Right, I’m beginning to choke on my own smugness now…

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