[vii]

It's hard to do objective research. Some studies try A/B tests on student volunteers. But then this setting is clearly different to professional teams working on a project for a long time.

The value of new methodologies, languages, and techniques is partly that the enthusiastic proponents of them are given a chance to prove out that there is value, and so become motivated to go the extra distance to achieve the project specific outcome.

This value is destroyed if people are forced to use the technique, instead of championing its introduction. So measurement is made even harder!