This week: Claiming benefits has been described by the Chancellor as - for some - a "lifestyle choice". What does the evidence tell us about how incentives work in the welfare system?; The numbers of some of Britain's best-loved birds are declining. Fast. Many think cats are to blame. Are they right?; Why the Prime Minister's salary has become a convenient unit of measurement; And we bring you the results of our mathematical attempt to level the playing field at this year's Great North Run half marathon.