Kai Ryssdal: If there was ever a case of being able to see the glass as either half-empty or half-full, today’s profit report from General Motors was it.

Take your choice of these two very different headlines — both of which, by the way, are true. On the one hand, GM posted a record profit of more than $9 billion last year. On the other, GM’s fourth quarter earnings fell short of analysts’ estimates.

Who exactly are those analysts? And what do they know, anyway? Here’s our senior business correspondent Bob Moon.

Bob Moon: Way back in 1933, a Harvard economist posed the question: “Can Stock Market Forecasters Forecast?” His study concluded: “It is doubtful.”

Fast forward, and little seems to have changed: Was GM’s profit really too weak? Or did analysts just get it wrong?

Rebecca Lindland: The reality is, this is a company that was on its knees just a couple years ago, and to be talking about record profits is what we really need to focus on.

Rebecca Lindland is an auto industry analyst for IHS Global, but she focuses on things like consumer satisfaction, and doesn’t make stock predictions. She says her Wall Street counterparts are merely making educated guesses. They talk to company managers, suppliers and customers, and come up with their estimate. GM came in below the consensus this around. Of the S&P 500 companies that have reported so far this quarter, two-thirds have beat expectations.

Barry Ritholtz: Too high to be an accident. Management has gotten so good at downplaying expectations that they leave themselves a lot of room to surprise to the upside.

Economist Barry Ritholtz contends corporate executives have learned to influence the analysts’ numbers with a wink and a nod.

Ritholtz: You know, your numbers — you’re way up there, you need to settle down a little bit. We’re not selling iPads, we’re selling, you know, dishwashing detergent. You gotta lower your numbers a little bit!

Ritholtz says in come cases, analysts can skew their numbers higher to improve sales for their investment banking firms. Those banks promised to wall off their research divisions years ago, but many on Wall Street say the cheerleading goes on.

I’m Bob Moon for Marketplace.