I think when I do a third edition of my"How to Win Every Argument" I will add a new fallacy to the 94 fallacies I identified and described there. This could be called "Measuring quality by inputs."

I wrote here earlier about "Regulation by result" making the case that if we state what result is to be achieved and leave it to creative brains to find ways of achieving it, we do better than if we stipulate the processes which people are required to follow.

This is different, but related. It seems extraordinary that people should measure quality by the effort put in rather than by the result achieved, but many people do precisely that. Gordon Brown's government measured the quality of education by the amount spent on it, by the pay of teachers, by the size of classes, and so on. Most thinking people would measure the quality of education by the ability of the children to read, write and do arithmetic, and to pass exams. It may be that the inputs listed contribute to an improved output, but that is not intuitively obvious. Measurement of the inputs is not a substitute for measurement of achievement.

It is very common for measurement of the quality of the NHS to be discussed in terms of how much is spent on it, or how many people work in its different departments, whereas many might suppose its quality would be better measured by the death rates for various diseases, or the brevity of recovery times.

We live in the real world, and want to know if it is improving in various respects. To do that we have to look at what happens in practice, rather than congratulating or criticizing the effort or the expenditure applied. Quality is what a thing is like – an outcome not an input.