When Donald Clark is older he will be classified as a full-fledged curmudgeon. As it stands now he is definitely a curmudgeon-in-training not to be missed with riffs like this debunking the abuses of big data (or in some cases, misinterpreted data, misleading data, or (in the case of Ken Robinson) no data whatsoever). "We must be wary of data when it is used to exaggerated claims through addition or subtraction or spearhead prescriptive programmes and extreme testing. I am appalled at the way politicians and educators take up PISA, PIAC and OECD data, with little or no detailed examination of their assumptions or relative values and use it to shape prescriptive policies that do more harm than good." Amen. (See also my essay Understanding PISA).