But it means another thing equally important--it means that 90 per cent of misses are made.

To what are these misses due?
Clearly they are due to errors made, not necessarily by the man who fires the gun, but by all the people concerned.

If the correct sight-bar range were given to the gun, and if the gun were correctly laid and the pointer pressed the button at precisely the right instant, the shot would hit the target, practically speaking.

But, in actual practice, the range-finder makes an error, the spotter makes an error, the plotting-room makes an error, the sight-setter makes an error, and the gun-pointer makes an error.

The sum total of all of these errors results in 90 per cent of misses.
Suppose that by careful training these errors are reduced in the relation of 9 to 8, so that instead of there being 90 per cent of misses there are only 80 per cent.