In all my letters (most recently, "The very definition of delusion", 3 January), I have consistently used the terms "educational assessment" and "measurement". So it appears that it is Mervyn Benford who is obsessed with the narrower activity of "testing", not I ("People drive learning, tests hold it back", 10 January). However, I am pleased that he acknowledges the important role played by surveys such as the Trends in International Mathematics and Science Study (Timss) and the Programme for International Student Assessment (Pisa) in providing objective evidence as to the most important factors in promoting effective learning. This is the result of relating quantitative data on background factors (collected using not "tests" but questionnaires) to the prime indicator of achievement - student scores on subject tests. QED.
George Bethell, Director, Anglia Assessment.