Just yesterday, I got my first taste of creating personas based on workers we've been observing recently. So far, the creation of these personas has been the most fun and interesting part of the project.
Suddenly, we see all the disparate data from Contextual Inquiry come together to create fictional characters that represent the various types of folks we've observed.
The more we get to know these fictional characters and match them with our targets, the more likely our future products are to match with the real worlds of the folks we're studying. It won't be long until we can say "Would Jeffery like this feature?" and If the answer is no, then we need to rethink it.
Jerry Michalski recently pointed me to this blog post that links to an article about how Best Buy is using personas.