Effect and Effect
Sometimes correlations are random and freakishly mysterious. For examples, check out the collected and recollected Spurious Correlations, by which we learn, among other things, that the divorce rate in Maine correlates with the amount of margarine consumed.
But often the correlation-related confusion has to do with mistaking effect and effect for cause and effect.
Take the classic correlation month-by-month between death by drowning and amount of ice cream consumed. At first it seems sort of random, like the divorce and margarine correlation. But with a little inspection, we see that both the rate of deaths by drowning and ice cream consumption are effects of a separate cause-- the weather. In the snow and cold of winter, fewer people eat ice cream, and fewer people go swimming.
Someone might look at pro basketball players and conclude, "Hey, they almost all have huge shoe sizes. That must have something to do with making them successful NBA players!"
When we confuse effect and effect for cause and effect, we start trying to implement ideas. Some politician says, "Well, clearly ice cream causes drowning, so let's heavily regulate ice cream sales so that we can reduce the number of deaths by drowning."
Or a parent says, "Clearly, if I start my child wearing really big shoes from an early age, he will CURMUDGUCATION: Effect and Effect:
Summative School Ratings: Not So Great
Chad Aldeman took to the Bellwether blog to make his case for summative school ratings (grades) under the loaded headline "Summative Ratings Are All Around Us. Why Are We Afraid of Them in K-12 Education?"
Of course, plenty of us, maybe even most of us, are not "afraid" of slapping a grade on schools. There just don't appear to be many benefits, and plenty of harm done. Aldeman provides a list of his positives. Let's see how they stack up.
1. Summative ratings are all around us.
Perhaps Aldeman somehow skipped that part of childhood where some adult authority figure said, "If everyone else jumped off a cliff, would you do it, too?" He correctly notes that ratings are all the rage, from Amazon to Rotten Tomatoes. But he also notes that customers who are interested in purchases will read the reviews, and reading through all the reviews on Amazon or Yelp is pretty much the opposite of a summative rating.
Of course, this sort of system doesn't always work out well. TripAdvisor, an app and service that collects reviews (and makes summative ratings) of hotels and motels, ironically itself gets a one star rating from Consumer Affairs, backed up by hundreds of tales of the rating service being skewed in any number of ways, often because of one sort of relationship or another with those being rated.
Aldeman might also have noted the long-standing summative rating used in the investment world, where investments are rated A or AAA or some lesser letter. If you think back to 2008 and all the Summative School Ratings: Not So Great