Durham County Council carried out a study into the effects of the fish oil dietary supplement on pupil performance during last year’s GCSE examinations. Over 3,000 Year 11 pupils took part in the study. Each of these students were then matched with a pupil of similar ability, gender, social background and school to form 629 matching pairs. The organisers of the study ensured that each pair’s Key Stage 2 results did not differ by more than 3 points. By comparing the Key...