Tuesday, April 13, 2010

Visualizing the Broad Street Cholera Outbreak

I don't know that this is big enough for you to make out the text (it gets bigger if you click on it!), but you don't need to read the words to get the bigger sense. I won't say much about the theory behind this, since my previous post got into some of that. Instead, I want to provide a brief description of the artifact and let it simmer.

First off, since the legend isn't on this, circles represent questions, squares represent questions, upwards-facing triangles represent hypotheses, downward-facing triangles represent experiments, and diamonds represent conclusions. On the whole, the diagram above represent the process that John Snow used while dealing with the Broad Street Cholera Outbreak in 1854. As you can see, there's a general tendency to move through the traditional steps of the scientific process, but it is notable that questions and observations pop up throughout, where experiments and conclusions are much more infrequent. Of course, the point is not to generalize here, but to open up dialogues: why might observations and questions be more prominent? Should they be?

There's also a lot of room for debate as to whether each node is assigned the correct shape. Some of the observations could be characterized as experiments, for example. Likewise, some observations might be conclusions. How can you separate a hypothesis from the question that leads to it? All of those are discussion points, and the purpose of this artifact is to help generate those kinds of questions.

One other important note here is the cloud down at the bottom right. Since we are planning on making a web-based tool that will help students generate process maps like this one, we also see the potential to jump off of existing questions (and data) in the direction of new discoveries. Historically, this is not uncommon in science, but the jumping-off process - like the narrower process of a single experiment - is usually quite obscure. We want to make it easier to find questions to jump off of, and to make it clear where that jumping off happens.

Anyway, in this artifact in particular, the cloud represents the process that generated germ theory. Snow himself, in solving the cholera problem, did not develop a theory as to why people were getting sick (beyond there being sewage in the water). The attendant question, "why does sewage in water make people sick," may sound silly to us today, but at the time there was no meaningful answer. Snow pursued a more practical path - getting the sewage out of the water - but left it to future scientists to address the bigger question.

Constructing historical exemplars of the dynamic scientific process will be an important part of our project, but in so doing we've already learned how important it is to be careful about phrasing. It is so natural to assume modern knowledge about, for example, bacteria, when in fact that was non-existent at the time Snow was operating. Even the question, "What was in the water?" presupposes things which at the time scientists had no reason to suspect. Of course, in being careful about historical knowledge, we're finding that there are discussion points we hadn't even considered.

Image Credit to Jericha.

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