Has the government taken into account the worth of a badger's life in any cost-benefit analysis of the badger cull? It aims to kill 70% of badgers in the two cull zones, but Tim Harford discovers that such precision might be tricky. Plus, have blundering doctors and nurses really killed 13,000 patients in England? Shadow immigration minister Chris Bryant has warned that climate change is going to create 200 million more migrants but, More or Less discovers, migration experts disagree. And, always down with the cool kids, Tim discovers more about this buzz phrase, "big data". Might it be telling the world our darkest secrets?