(n.) The defacto gold star standard for delivering products and/or services within a projected timeframe. Derived from the original Star Trek series wherein Lt. Cmdr. Montgomery 'Scotty' Scott consistently made the seemingly impossible happen just in time to save the crew of the Enterprise from disaster.
The premise is simple:
1) Caluculate average required time for completion of given task.
2) Depending on importance of task, add 25-50% additional time to original estimate.
3) Report and commit to inflated time estimate with superiors, clients, etc.
4) Under optimal conditions the task is completed closer to the original time estimate vs. the inflated delivery time expected by those waiting.
The following situation is a simulation of the Scotty Principle in practice.
Kirk: "The ship seems sluggish today. When was the last time you did a tune-up on the warp drive?"
Scotty: "Aye, sir. She's due. Last maintenance was 56 days ago."
Kirk: (light chuckle) "Well, what are you waiting for? An ambush from cloaked Romulans?"
Scotty: "I'll need to check how much dilithium we have in supply, but she'll be better than new in no time."
Kirk: "And that will be...?"
Scotty: "Six hours."
--- four hours later ---
Scotty: "All done, sir. Care to test her out?"
--- Enterprise taken rapidly to warp 3, does a few doughnuts, comes to a smooth stop ---
Kirk: "Scotty, there's no finer engineer in this quadrant!"