 This provided the necessary legal, demographic, financial and statistical background to the Review and an important resource for its consideration of policy options.The Review also searched relevant OECD and other international data.The balance of evidence The four evidential strands sought to balance opinion-seeking with empirical data; non-interactive expressions of opinion with face-to-face discussion; official data with independent research; and material from England with that from other parts of the UK and from international sources.