How about making comparative test where one subject has suboptimal conditions?
- no objective given, or change objective in middle of test
- no IDE allowed, only notepad and outdated compiler
- place next to garbage bin or turbofan engine
- randomly generate some 'legacy code'. Result must contain 90% of this code...
- no internet connectivity allowed
- no external libraries allowed...
- code must be deployed within 1 week, it must past code-review before deployment, reviewer is on holiday....
- ask subject some trivial question every 10 minutes. Or thrown in 5 hours meetings randomly.
I am sure the productivity will vary... :-)