Study objective: In social epidemiology, it is easy to compute and interpret measures of variation in multilevel linear regression, but technical difficulties exist in the case of logistic regression.

Data that have a multilevel structure occur frequently across a range of disciplines, including epidemiology, health services research, public health, education and sociology. We describe three ...

Former Secretary of Defense Donald Rumsfeld pointed out an important principle of business intelligence in his briefings when he talked about finding unknown unknowns. Known unknowns are questions ...