Misconception Mutt extract from chapter 12
The Misconception Mutt had been trying to train his owner. Every morning he tried doing a trick to see whether his owner would give him more grains for breakfast. He’d tried paw, rollover, and the classic spaniel move of just rolling around on his back with a crazy look in his eye and his tongue lolloping out of his mouth. If only there were some way he could compare the average amount of food he received after each trick. While his owner was asleep, the mutt had found his statistics textbook and rested his head on it. He found that written words drifted into his brain if he slept on things. Apparently he needed an ANOVA.
The next morning as he munched his grains, he muttered to himself about using an ANOVA to compare means. His dog flap clanked shut, making him jump on his heels to turn. There was nothing there. As he turned back to his bowl he noticed a large ginger cat helping himself to his food. The mutt growled.
‘You know,’ said the cat, ‘ANOVA is the same thing as the linear model or regression.’
The growling continued.
‘The reason why some people think of ANOVA and regression as separate statistical models is historical. Two distinct branches of methodology, correlational and experimental, developed in the social sciences. Researchers interested in controlled experiments adopted ANOVA as their model of choice, whereas those looking for real-world relationships adopted multiple regression. With the divide in methodologies came a chasm between the statistical methods adopted by the two opposing camps (Cronbach, 1957, documents this divide in a lovely article). Never the twain shall meet, and all that.’
The mutt growled some more.
‘Don’t feel bad. For decades researchers have gone around oblivious to the fact that they were using the same model under different names. Students are often taught “regression” and “ANOVA” in different contexts as though they are different. But now, my canine friend, you know better. Nice grains, by the way.’
With that, the cat finished the last of the dog’s food and darted out of the dog flap, leaving a ginger vapour trail.
