Not all statistics are created equal. Take a look behind the scenes and you'll discover that even most official data isn't the solid bedrock we think it is. It's patchy, inconsistent, full of guesswork and uncertainty - and it's playing an ever-bigger role in policy decisions.

BAD DATA takes the reader on that behind-the-scenes journey, guided by House of Commons Library statistician Georgina Sturge. Revealing the secrets of a world that is usually closed off, it will show how governments of the past and present have been led astray by bad data and explain why it is so hard to count and measure things, and how we could better handle these problems.

Discover how one Hungarian businessman's bright idea caused half a million people to go missing from UK migration statistics. Find out why it's possible for two politicians to disagree over whether poverty has gone up or down, using the same official numbers, and for both to be right at the same time. And hear about how policies like ID cards, super-casinos and stopping ex-convicts from reoffending failed to live up to their promise because they were based on shaky data.