The spokesman for the Qualifications and Curriculum Authority who described the OCR exam marking scale for A-level psychology as "valid" misses the point completely (TES, November 22). The issue is not the validity, but the reliability of the scoring of this module. Only from the reliability can we estimate the error of measurement and, hence, the number of candidates who may have been given the wrong grade.
Cambridge Assessment and Development in Education
Stone Croft Valley Road Battisford