For instance, if a man handles an organization with the intent thereby to produce a certain result, the organization is the instrument whereby he attempts to produce the result.
If a man exercises perfect skill, he achieves with his instrument 100 per cent of its possible effect.

If he exercises imperfect skill, he achieves a smaller percentage of its possible effect.
To analyze the effectiveness of skill, let us coin the phrase, "effective skill," and agree that, if a man produces 100 per cent of the possible, his effective skill is 100 per cent, and, in general, that a man's effective skill in using any instrument is expressed by the percentage he achieves of what the instrument can accomplish; that, for instance, if a gun is fired at a given range under given conditions, and 10 per cent hits are made in a given time, then the effective skill employed is 10 per cent.
From this standpoint we see that imperfect skill is largely concerned with errors.

If a man uses, say, a gun, with perfect skill, he commits no error in handling the gun; and the smaller the sum total of errors which he commits in handling the gun, the greater his effective skill and the greater the number of hits.
The word "errors," as here used, does not simply mean errors of commission, but means errors of omission as well.

If a man, in firing a gun, fails to press the button or trigger when his sights are on, he makes an error just as truly as the man does who presses the button or trigger when the sights are not on.
Suppose that, in firing a gun, under given conditions of range, etc., the effective skill employed is 10 per cent.

This means that 10 per cent of hits are made.