But What Does It Mean? The use of effect sizes in educational research

Ian Schagen, Karen Elliot

14 June 2004

'But what does it mean?' - a question that is increasingly being asked, in particular by policy makers and practitioners, about the results from sophisticated analyses. They are right to demand that complex results are presented both validly and accessibly, but how can researchers and academics meet this need?

One approach is through the use of 'effect sizes', a way of presenting the relationships between background factors and outcomes which can make them easier to compare and understand. In November 2003 an invitational seminar, jointly organised by the Institute of Education, University of London and NFER, discussed how this concept can be applied to complex educational analyses. Six papers were presented, three discussants added their views, and a lively general debate continued on the day and through a website discussion forum afterwards. This book details the seminar proceedings.