Missile turret placement

Whenever I scout a build that has potential for airborne harassment (e.g. Banshee, Muta, Oracle) my reaction is to build missile turrets to defend the mineral line, however all too often my opponent manages to find a spot where they can still get free shots at my workers. (I generally place my turrets beind the mineral line)

How should I place missile turrets to properly defend against airborne harassment?

I will always recommend placing the Turret inside your mineral line - for several reasons.

• It covers the entire mineral line. There is no "sweet-spot" for whatever early harass your opponent might throw at you.
• Easy to repair placement. The Turret can get a complete suround by your SCVs, repairing the Turret instantly. By this, they dont need to move around the minerals, only to have 2-4 SCVs repairing and possibly fail the repair.
• It comes at a minor mineral loss, due to a "block", you probably won't notice any difference by having a Turret in your line of minerals.
• You can manage early harass easily and cheaply by only building 1 Turret in your mineral line.

EDIT:
There is usually a gap between your minerals somewhere in the middle. That is where you would want to place your turret, as it would still protect the entire mineral line and it does not obstruct the workers that much.

EDIT: I added two pitctures from WCS EU showing players placing turrets inside thier mine lines. Like explained, it is the best position.

On the Team Liquid forum, there was some research done about this. The research was done in 2010 for Wings of Liberty, but should still be mostly valid.

User Fork posted some replays with math in this thread, and came to these conclusions:

1. It is better to place turrets next to the CC, not by the minerals.
2. Placing turrets in your mineral line may lower income by ~6% (50 minerals/minute out of 700-800; this is equivalent to the loss of one worker)
3. Surprisingly, scooting your CC back 1 space and then building the turrets diminishes the income penalty (However, the income loss from lifting off and re-landing was not accounted for).

Also, here is another thread (also from 2010) which backs up point #1: Even up to 3 buildings placed next to a Nexus had minimal effect on gathering rate (!50 minerals/minute, about the cost of one worker).