> Any worthwhile development practice must have objectively measurable results....
I thought you were asking for objectively measureable results in isolation. You'll still have terrible trouble trying to isolate a single variable (and good luck with a control group for a creative design activity!), but I suspect you can get decent results by measuring the cost of a change, the correctness of a change, and the amount of rework in a change when using TDD.
Comments
Have you read Bob Martin's "TDD Triage"? It offers a lot more nuance than you might suggest: http://blog.objectmentor.com/articles/2009/10/08/tdd-triage
> Any worthwhile development practice must have objectively measurable results....
I thought you were asking for objectively measureable results in isolation. You'll still have terrible trouble trying to isolate a single variable (and good luck with a control group for a creative design activity!), but I suspect you can get decent results by measuring the cost of a change, the correctness of a change, and the amount of rework in a change when using TDD.