Recent criticisms of the Programme for International Student Assessment (Pisa) have clearly touched raw nerves in the assessment industry (“Don’t hide behind jeers and sneers”, Letters, 13 December).

Two clear camps are emerging in the battle over testing. There are those who, like letter writer George Bethell, believe it is possible to define the slippery concept of “quality” in education; there are others who believe it is indefinable. There are those who believe it is possible to measure quality through testing, and others who believe that quality can only be judged, although that judgement can be informed by test data.

For the first group, good-quality education provides experiences leading to high test scores; for the second, it involves giving young people a multitude of experiences that enable them to learn and flourish, as well as providing them with the understanding, skills and self-confidence to go on learning (and flourishing) long after they have completed their final test or exam.

Colin Richards, Spark Bridge, Cumbria.