Science Fictions: How Fraud, Bias, Negligence, and Hype Undermine the Search for Truth

by Stuart Ritchie

When it comes to studies of such extraordinarily complex systems as the body or the brain, or an ecosystem, the economy or society, it’s rare for scientists to find one factor that has a massive effect on another. Instead, most of the psychological, social and even medical phenomena we’re interested in are made up of lots of small effects, each of them playing a small role. For example, if economists want to explain why different people in their sample have different incomes, they’d need to take into account where the participants live, their family backgrounds, their abilities, personalities and education, their country’s tax system and its changes over time, and a whole host of other factors and experiences that might have nudged the participants’ fortunes in one direction or another throughout their lives. The fact that small effects are so much more common and, collectively, so much more influential than big ones makes underpowered studies, which portray a world full of large effects, all the more misleading.