If, as Colin Richards suggests, educational quality is truly “indefinable” (“Quality can be tested? Wrong answer”, Letters, 2027 December) then, by definition, there can be no meaningful discussion of the concept - we cannot understand, control or improve it. If, however, key aspects can be sufficiently well described then measurement instruments (not necessarily “tests”) can yield data to inform our discussions and shape our decisions. Without such data we have only opinions. From the same side of the divide, Mervyn Benford cites six factors that he says “are the essence of effective learning”. Is this his opinion or based on verifiable data obtained through evaluation? If the former, then it warrants no more credence than anybody else’s proposition. If the latter, then it both negates his specific challenge to me and proves my general point - if a construct can be defined then it has the potential to be measured.

George Bethell, Director, Anglia Assessment.