Why is data on grooming gangs so bad?

In this episode of More or Less, Tim Harford and Josephine Casserly delve into the complexities of data surrounding group-based child sexual exploitation, highlighting the misleading nature of reported ethnicity statistics due to a high percentage of missing data. The discussion reveals that while initial reports suggest a majority of perpetrators are white, a significant portion of cases lack ethnicity data, skewing the overall picture. Later, the podcast explores the science behind nuclear enrichment with Professor Geoff Parks, explaining the process and implications of Iran's nuclear program. Finally, the episode examines claims made in Adam Curtis's BBC documentary "Shifty" regarding Margaret Thatcher's 1979 election campaign, with Sir John Curtis debunking assertions about Thatcher's stance on immigration and its impact on poll results. Duncan Weldon then discusses his book "Blood and Treasure," applying economic analysis to historical conflicts, including the surprising potential economic benefits of Viking raids.