edgeEye.blog is a series of idea droppings from Lee Allen.Archive / RSS
Selection bias in iTunes app store ratings
Selection bias (e.g. Berkson’s bias) is a distortion of evidence or data that arises from the way that the data are collected. It is sometimes referred to as the selection effect. The term “selection bias” most often refers to the distortion of a statistical analysis, due to the method of collecting samples. If the selection bias is not taken into account then any conclusions drawn may be wrong.
When you remove an application from your iPhone, you’re asked to rate the application. It’s fair to assume that people who remove an app would rate it lower than those who don’t. This seems to qualify as selection bias and I’m curious if it is skewing app ratings downward unfairly.