anscombeAn article from Jodi McDermott re-introduced me to something I haven’t heard of in years, Anscombe’s Quartet.  For the unknowing, it’s a collection of 4 small datasets that when analyzed statistically are identical (same min, max, mean, and variance).

What’s my point, you might ask? When each one of these datasets is plotted out visually, they have completely different appearances (just click on the link above and you’ll see what I mean). There are outliers where one would not expect to see them — identifying both opportunities and risks in your data depending on what you are analyzing. However, one would never see the variance in data patterns if it was not plotted in a chart or graph (or analyzed data point by data point).

via MediaPost Publications Visualizing Data 09/04/2009.