I’ve been working on a project where we’re trying to come up with a way to establish a visual design “clutter index.”  The goal is to see if there is some threshold beyond which web page clutter impacts business metrics like conversion and click-through rates.  The challenges are widespread of course, and mainly focused on the following 3 areas:

• The definition and measurement of clutter.  There are a variety of ways to measure clutter on pages, ranging from the completely objective (e.g., % of white space on a page) to completely subjective (e.g., how do users rate the page on a clean vs. cluttered scale).
• The definition of conversion.  Since some pages on an e-commerce web site are revenue-generating, and others aren’t, an important question is how you define conversion.  For revenue-generating pages (e.g., pages with a “checkout now” button) this is easy — “Did the page result in a sale?”  For other pages, like product information pages, this measure won’t work, so some other measure of engagement with the page becomes necessary.
• Controlling for other influencing factors.  In conjunction with the first two points comes the problem of causality vs. correlation.  Assuming you have your definitions of clutter and conversion nailed down, how can you be sure any changes you see in conversion is caused by clutter (causal relationship), and not some other factor you are not accounting for (there’s correlation but no causal relationship).

The way to go about it is to take as many measurements of clutter as you can, feed them into a statistical model with a variety of conversion metrics, and see what comes out.  You also have to find a way to account for other influencing factors so that you can control for that in your model.  Easy, right?  Ok, so there are a lot of open issues, but they’re definitely not insurmountable.  I also believe it’s a worthy pursuit, the hypothesis being that there are clear business reasons for keeping designs and interfaces simple.

And apparently we’re not the only ones thinking about this…  Ruth Rosenholtz and her colleagues at MIT recently wrote a paper (Measuring Visual Clutter) where they seem to have developed what they call a “clutter detector” for a variety of interfaces, mostly offline (desk clutter, map clutter, etc.).  They describe some of their challenges in doing this as follows:

The fact that one person’s clutter is the next person’s organized workspace makes it hard to come up with a universal measure of clutter. Rosenholtz and colleagues modeled what makes items in a display harder or easier to pick out. They used this model, which incorporates data on color, contrast and orientation, to come up with a software tool to measure visual clutter.

On the issue of subjective measures of clutter:

Although there was a fair bit of disagreement among the people being tested about what constituted clutter, when the researchers compared results from their clutter measure to those of their human subjects, they found a good correlation.

I’m still digesting the paper, but it’s a fascinating read so definitely check it out.  Thoughts on how to approach this for e-commerce web pages are also more than welcome!