Earlier this year, a baker in Liverpool in north-west England vented her frustration on Twitter over constantly being asked by social media influencers for free cakes. Many other businesses publicly sided with Laura Worthington, but were they being fair? We investigate the impact of influencers – people with powerful social media followings. What are the rules and ethics around advertising and promotion? What proportion of your country are immigrants? What proportion of teenage girls give birth each year? Research suggests most people get the answers to these questions, and many others about their own countries, very wrong. Tim Harford interviews Bobby Duffy, Global Director of Ipsos Social Research Institute and author of the book, Perils of Perception: Why We’re Wong About Nearly Everything. Heartbreak after love lost has been written about for generations in literature and in songs. But what causes this physical feeling of pain? Is it a figment of our imagination, prompted by our society and culture, or can we fall sick or even die from a broken heart? Photo Caption: Influencer Lisa Linh promotes a number of brands – including hotels and credit card companies Photo Credit: Lisa Linh