It was the early 1990s, and I was in grad school at the University of Oregon. I was in the Public Affairs program taking an economics class, and our professor was giving an example of how baseline data matters.
Some years earlier, he’d lived in Salt Lake City, and he started noticing something as he drove around town: He was seeing a noticeable number of cars with the kids not in carseats. So many, in fact, that he began to question if people there were concerned for their children’s safety.
He knew this thought was wrong. Family is precious to Mormons, literally sacred in fact. There had to be something else involved, and, being an economics professor with a strong grounding in statistics, he finally figured it out: Baseline.
Simply put, there were so many young families in SLC, so many people driving with kids in their cars, that of course he was seeing more cars without carseats than he was used to. He had not accounted for the change in baseline: the fact that he was also seeing more cars-with-kids than he was used to.
The baseline for “families with small kids in cars” is pretty big in Salt Lake City. So if they have the same ratio of cars not using safety seats as, say, Portland, the gross number is going to be larger. Those cars will stand out because there are more of them.
When we look around us and make an observation about public behavior – eg, the number of rude, inconsiderate, scofflaw bicyclists – we have to understand the baseline data. In Portland, we have a relatively huge number of people riding bicycles, even in bad weather. Because we do have as many bicyclists as we do, even if only a small percentage are the jerks, we’re going to have a lot of those jerks in total.
And the jerks stand out, just as the cars without carseats did. We have to see the big picture, the overall numbers.
A couple of examples:
Hillary Clinton got more votes for president than anyone else ever has except Obama, but we also have more voters now.
The new Star Wars movie is like to make more money than any other movie, but ticket prices are also higher.
Baseline data is critical: We have to know the lay of the land, the raw numbers (amounts, quantities, ratios), the firmament on which to construct hypotheses and studies. Or even assumptions.
So when you are tempted to conclude that “Golly there sure a lot of jerks doing such-and-such”, take a step back and look at how many of “them” there are in total. In many cases, you’ll discover that there are a lot in terms of raw numbers but, as a percent of an overall population, the number of jerks or whatever is not very large.
Five percent of bicyclists being jerks is a lot of people in Portland. In Kansas City, MO, a city nearly the same size as here, it’s not a lot of people because there are far fewer bicyclists.
“Lots” is not a number. It’s a perception. Perspective is needed to get a grasp on the reality, and that means: get some good baseline data.
Or, to be a bit rude about it, know what you’re talking about.