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Magenta Book

Guidance Notes on Policy Evaluation

'...effective policy making must be a learning process which involves finding out from experience what works and what does not and making sure that others can learn from it too. This means that new policies must have evaluation of their effectiveness built into them from the start ...'

Professional Policy Making in the 21st Century (pdf), Cabinet Office, 2000

The Government Social Research Unit has prepared this set of guidance notes on policy evaluation and analysis to help 'intelligent customers' and 'intelligent providers' determine what constitutes high quality work in the field on policy evaluation and analysis.

These guidance notes complement HM Treasury's Guide to Economic Appraisal, which is more commonly known as The Green Book, and other sources of guidance from within government.

These guidance notes have been written by GSRU staff and by senior colleagues from the academic and wider research and evaluation community. They will be updated regularly to keep abreast of developments and innovations in the field of policy evaluation and analysis.

Use the hyperlinks in the table below to view the chapter that is of interest to you. More detailed, versions of the chapters are also available for downloading or printing.


  1. Introduction to the Magenta Book


  2. What is Policy Evaluation?
  3. What do we already know? Harnessing existing research
  4. What do the statistics tell me? Statistical concepts, inference & analysis
  5. What is sampling?
  6. How are the data collected? Data collection and survey design
  7. Why do social experiments? Experiments and quasi-experiments for evaluating government policies and programmes
  8. How do you know why (and how) something works? Qualitative methods of evaluation