Dino Nuggets and Snotties versus Simpson's Paradox
Apr 24, 2007 8:02 AM
Last week's news had the story from NC State University that dinosaurs probably tasted like chicken, and this week's Discovery Planet episode brought us the vivid scenes of the living snottie cave ceilings of Cueva de Villa Luz, an acid fuming cavern in the Tabasco state of Mexico.
So how can statisticians compete for attention with those juicy stories? Well it turns out that Leonard Stefanski made the local news headlines with research just published in American Statistician. You analyze certain data sets and examine the residual-by-predicted plot, and check for any patterns in the plot. This simple and routine practice can, with special data, lead to surprising patterns that reflect a regression in a different sense. I haven't seen patterns like this since the Coleman pollen data. Stefanski has it right. You have to check the graph, not just look at the estimates and p-values.
This is the central message embodied in JMP, look at your data and check for patterns and points that don't fit patterns. Now, please go to your web browser, search on three words: Homer Simpson Stefanski, follow the links, and see the patterns.