Two purple dragons stand next to teach other. They look similar, but one has stripes and one has spots. Multiple regression estimates are shown at the top, in the form of an equation: "weight (tons) = 2.4 + 0.6*spotted +..." Text reads. "pattern reference level: striped" and highlighting the 0.6 coefficient text reads "if other variables constant, spotted dragons are expected to weight 0.6 tons more than striped dragons, on average."