BLOG: Ohh, that pesky SAAR figure

In August, 997,574 autos were sold in the United States. That's a fact.

But what does it mean? How does it compare? Who won? Who lost? Why?

That's analysis. And that's where the fun comes in.

And of all the tools used to analyze sales data, the seasonally adjusted annualized sales rate (SAAR) is potentially the most confusing. It's designed to level out the differences in demand over the years -- and the months. Hot Augusts vs. icy Januarys.

Everybody has a different process. So everybody has a different SAAR.

Today's numbers are a perfect example. The Automotive News Data Center says August's SAAR is10.8 million, the lowest since February's 10.4 million.

So far, I've seen SAARs of 11.4 million and 11.5 million reported by other number crunchers.

In July? Bloomberg, Automotive News, and AutoData all were pretty close to 11.5 million

Why the August difference?

Different processes, mostly, although some SAARs include medium and heavy-duty truck sales. We do not: only passenger cars and light trucks, up to say, Ford F-350s.

The differences can come in how the number is calculated. Some use a longer base period, or a shorter one. Maybe one SAAR throws out the highest and lowest number to reduce outliers and another method doesn't. Others may have a complicated mathematical formula.

We've been calculating our SAAR the same way for close to two decades.

My suggestion to save your sanity: Only compare SAARs from the same source. Apples and apples, oranges and oranges.