Danny Dorling and Richard Austen-Baker are wrong if they think the purpose of a socioeconomic classification is to measure income (Letters, June 4).
A good classification should measure the underlying structure that determines people's incomes and life chances, which is what the National Statistics Socio-Economic Classification does. Contra Dorling and Austen-Baker, the schema does correlate highly with employee earnings. It does not, as Dorling asserts, confuse the rich and the poor. Moreover, unlike the old classifications, it suggests causal relationships between class and other forms of inequality, including income inequality. Of course, I accept that some researchers may wish to use income rather than social class as a measure of inequality, but let's not confuse the two.
I am sorry if Austen-Baker prefers irony to scientific statements, but then he is a lawyer. However, the figures given in the New Earnings Survey for employee earnings come directly from employers and so are as accurate as we are ever likely to get. Perhaps some self-employed plumbers are on £50,000 a year, but that is precisely why people in the same occupation are not necessarily in the same social class.