Randomized experiments (or randomized controlled trials, RCT) are a powerful tool for testing causal relationships. Their main principle is random assignment, where subjects or items are assigned randomly to one of the experimental conditions. A classic example is a clinical trial with one or more treatment groups and a no-treatment (control) group, where individuals are assigned at random to one of these groups. Story 1: (Internet) experiments in industry Internet experiments have now become a major activity in giant companies such as Amazon, Google, and Microsoft, in smaller web-based companies, and among academic researchers in management and the social sciences. … Continue reading Key challenges in online experiments: where are the statisticians?