Damned statistics 3

Pay discrimination between ethnic-minority and other staff is impossible to verify if variables such as qualifications, age and experience are not taken into account ("St Andrews attacked on ethnic pay", THES , June 14).

The argument that small numbers of ethnic-minority staff in some universities are further evidence of discrimination is also invalid.

Before one could draw such a conclusion it would be necessary statistically to control for factors such as the number qualified in subjects prominent at a particular university, the number applying for teaching posts and how their qualifications and experience compared with those of other applicants.

Michael Davenport
Edinburgh