This blog entry notes how easy it is to fool yourself into thinking that a screening program is doing well because it finds problems “early while you still have a chance.” It outlines problems with non-randomized studies that are prone to selection bias, length bias, and lead-time bias. It also explains what these biases mean in non-technical language.
Bastian H. “What’s so good about “early,” anyway?” Statistically funny blog. 2013 (December 29). Excerpt: “The “get in early!” assumption has an in-built tendency to lead us astray when it comes to detection of diseases and conditions. And even most physicians – just the people we often rely on to inform us – don’t understand enough about the pitfalls that lead us to jump to conclusions about early detection too, well…early.” Available at: http://statistically-funny.blogspot.com/2013/12/whats-so-good-about-early-anyway.html.