Research evidence helps us develop an understanding about things happening in the world. This can include how effective a new technology is to why people behave in certain ways. What sets research evidence apart from other forms of information (such as hearsay, anecdotes or opinions) is the way that it is collected and analysed. Research evidence comes from studies that follow a research process.

The Parliamentary Office of Science and Technology (POST) reviews and presents research evidence through briefings called POSTnotes and POSTbriefs. These resources are for people who read research to inform their opinions or to help them scrutinise legislation and policy decisions. It is not intended for those who commission or conduct research. This is because it does not focus on practical considerations (such as cost or length of delivery) and does not cover methods used for policy evaluation. Those interested in how to design, use and understand policy evaluations may find HM Treasury’s Magenta, Green and Aqua Books helpful [1, 2, 3]. There are dozens of different research methods and it is not possible to cover them all in one document. Therefore, this set of resources describes the different research methods most commonly cited in POST’s work. It is also not possible to cover all the complexities and nuance around research methods and so this briefing simplifies some concepts for ease of understanding.

In this work:

  • We describe research methods used to generate evidence.
  • We explain some of the most common study types, including discussing what different studies can and cannot tell us.
  • We present some of the most common ways of collecting data.
  • We describe some of the most common ways of analysing data.
  • We discuss some considerations when interpreting research evidence, including how researchers assess the quality of evidence and how confident we can be applying the findings of studies to the ‘real world’.
  • These resources are accompanied by a research glossary where you will be able to find definitions to many of the most widely used research terms.

In this series you will find


  1. HM Treasury (2011). The magenta book: Guidance for evaluation. UK Government.
  2. HM Treasury (2013). The green book: appraisal and evaluation in central government. UK Government.
  3. HM Treasury (2015). The aqua book: Guidance on producing quality analysis for government. UK Government.


POST would like to thank the following peer reviewers for kindly giving up their time during the preparation of this briefing:

Alliance for Useful Evidence (Jonathan Breckon and Kuranda Morgan)

Dr Deborah Bailey-Rodriguez, Middlesex University London

Dr Adam Cooper, UCL

Rob Davies, CLOSER

Neil Drake, National Institute for Health and Care Excellence

Dr Andi Fugard, Birkbeck

Professor David Gough, EPPI-Centre

Professor John MacInnes, University of Edinburgh

National Audit Office (Margaret Anderson, Meg Callanan and Ruth Kelly)

Professor Melanie Nind, National Centre for Research Methods

Dr Kathryn Oliver, London School of Hygiene and Tropical Medicine

Dr Martin Ralphs, Office for National Statistics

Dr J Simon Rofe, SOAS

Professor Jennifer Rogers, PHASTAR

Dr Alex Sutherland, Behavioural Insights Team

Dr Ben Taylor, Open Innovation Team