Passing Trains

The following messages came in through my Twitter (and Facebook) stream within a 15-minute span Monday morning:

Laura Howe: wow! metro is really quiet this am. hardly anyone on board for a monday morning.

Rick Murray: Want proof people are driving less: Metra has added a car to this train = 250 more folks doing the green thing downtown.

Two trains, two cities, two divergent opportunities to make an observation. That’s what we do, gather input and try to reorganize it into some semblance of understanding. It’s easier to remember conclusions than the steps it took to get there. It’s easier to remember the final score of a game than a comprehensive list of the plays. The trick is to remember the information that is significant.

Finding the Factor

In geometry, we have theorems – postulates that aren’t true by definition, but have been proven true by experience and derivation from other known truths. We fail when we skip to a new derivation without enough fact to support it. And we do that far too often.

Take Rick’s assertion. Is it indeed a sign of the times? Are there more commuters avoiding high gas prices? Is he basing this on a personal observation or just reading a news release from the operators of Chicago’s Metra?

Now look at Laura’s message. The Metro (DC) is eerily quiet. Does that entail a drop in ridership? Or is there a federal holiday underway, not uncommon for a Monday? Or are more people taking cars?

Truth is, we don’t know. We don’t have enough information. Such a message (or observation) remains strictly anecdotal out of context. Maybe Metra is adding a car in anticipation of behavior that will not materialize. Who knows?

Shortcuts Can Miss the Truth

All too often, we over-apply Occam’s Razor and end up buttressing our previously-held beliefs with new ‘evidence’ that might not apply. Take Laura’s case. How many reasons might there be for such a small number on her train:

• Holiday
• More people are driving cars than before
• Previous train was later than normal, giving a smaller “gap of opportunity” for riders
• Connecting train was late
• Erroneous report that trains were closed
• Laura got on an unusually empty car

Again, who knows? But human nature tells us that when we carry a powerful narrative, we’ll tend to lean in that direction. If you are just convinced that we’re in the worst economy ever, you might even believe no one is on the train because everyone else is at home after a layoff. If you’ve just heard about a flu outbreak, you might blame it on that. Or, if you know there is a parade that day, you might assume people are attending that event instead.

The misapplication of Occam’s Razor occurs when we choose to believe the simplest explanation that matches our preconceived worldview, instead of just the simplest.

And the simplest isn’t always correct – just more likely to be.

Now – for fun – please chime in with your ideas. Come up with your own possible explanations for why Laura’s train might have been unusually empty. Or, share your theories about why Metra is adding a car that might have nothing to do with “going green.”

[tags]Ike Pigott, Occam’s RazR, statistics, occam’s razor, postulates, theory[/tags]