I have been invoking the inimitable Yogi Berra a lot recently; in particular, his observation about a restaurant that was so busy that no one ever went there.

Perhaps unwittingly, Yogi highlighted one of the effects that makes auto sales forecasting tricky these days. It is that people modify their actions based on what they believe to be true, instead of what is actually true.

Acting together, these individual adjustments can materially change how events play out. Looked at another way, because individuals rarely think about how others will react, the individual adjustments result in what is in the aggregate an overcorrection.

A great example occurred in 1984 when the city of Los Angeles played host to the Olympics. Months before the games, L.A. residents heard horror stories of the predicted traffic gridlock. When the games took place, traffic was actually lighter than seen in years.

Fast forward to today and the earthquake and tsunami that occurred in Japan back in March quickly led to headlines about global supply chain disruptions and zeroed in on supply shortages of Japanese vehicles.

Consumers reacted in late March and early April by moving up purchase plans. Japanese automakers reacted by reducing incentives and dealers similarly raised prices. Sales started slowing by mid-April, and the pace of the sales decline increased by the end of the month.

Conversely, because they believed supply was better and prices lower, consumers interest in Detroit- and Korean-made vehicles has jumped.

As an example, the number of Toyota Camry shoppers who also considered a Chevrolet Malibu has doubled in the past six weeks, according to Edmunds.com data.

But here’s the anomaly: looking at days-to-turn — an indication of demand versus inventory as it measures the time between a vehicle being delivered to a dealership and a customer buying it — shows supply is actually dropping faster for Detroit vehicles than for Japanese vehicles.

If this continues, the supply of Detroit — not Japanese — vehicles might actually be the bigger headache for consumers this summer.

Perhaps Yogi Berra should have tried his hand at auto sales forecasting. He seems to have always been right. Except, of course, when he was not.

Jeremy Anwyl  is the chief executive officer of Edmunds.com.