We make a huge deal of the employment numbers, and I can understand that. It's a decent gauge of the U.S. economy. It's certainly a political hot potato.

But when it comes to numbers that should matter to the stock market, it's hard to beat the earnings report we'll get Tuesday from Alcoa (AA).

I know at times I have cursed at the prospect of a stumbling Alcoa kicking off earnings season with a miserable first quarter. The number of times this company seems to miss estimates is boundless. The tone it creates makes people cringe, and because it is the long standout of a new season -- there's not much else that happens Tuesday -- it can be the backdrop for at least a full day's chatter.

How unfair that this stumblebum set the tableau, I always used to say.

But while you may not like how Alcoa does, believe me, if it is bad, it is no longer Alcoa's fault. The last quarter was actually a gem with good guidance.

But the issue isn't Alcoa itself and its execution or lack thereof. The issue is Alcoa sells into pretty much every market that matters. In that way Alcoa is my own barometer of worldwide growth, a far more important tell for things, for example, than a now totally politicized labor report. (And, yes, I am still steamed by the steamroller that ran me over for saying that the employment number was good and that it wasn't phony. Oh my, how I hate politics, and does it ever get in the way of thinking and making money.)

Consider the markets in which Alcoa plays a crucial role.

First, Alcoa is the dominant raw-materials supplier to aerospace, a business that employs millions of people worldwide. An astounding 1 million Alcoa screws go into each 787 or A380. All plane production uses aluminum. So I don't know how you are going to get a better read on this important industry, certainly not from the individual plane makers. Oh, and let's not forget that Alcoa's aluminum is the skin of choice for Navy and Air Force jets, so we will hear our fiscal cliff chatter for the quarter from this company. 

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Third, construction. You need Alcoa's building materials to skin buildings. Commercial construction uses a huge amount of aluminum. It's commercial construction that's lagged so badly. Lately we are hearing of a turn. Alcoa will tell us whether it is real.

Fourth, we have a tremendous amount of switching to gas turbines from coal utilities. But there's no real way to judge the growth, because of the disparate turbine makers, but they all use Alcoa aluminum. So we will get a read on one of the most important secular switches now in place.

Fifth, Alcoa makes drill pipe, the kind we use for deep finds of oil. It's the only game in town. We will get a nice insight from them.

Sixth and finally, aluminum, courtesy Steve Jobs, has become an important part of the technology chain. That, plus bottles and cans and wrap, all present insights into the worldwide consumer.

Unfortunately Alcoa also makes ingots and alumina, the raw and even rawer part of the aluminum chain. That's pure commodity, and that's what keeps Alcoa down, because financial interests -- hedge funds -- dominate that market. It's there that the shortfalls keep coming, in part because of Chinese overproduction and in part because hedge funds keep banging the stuff down.

No matter. Alcoa will give us a huge and important statement of where the world is heading. Don't dismiss it. Consider it the equivalent of a worldwide labor report without any chance of the alleged shenanigans.

Jim Cramer is a co-founder of TheStreet and contributes daily market commentary to the financial news network's sites. Follow his trades for Action Alerts PLUS, which Cramer co-manages as a charitable trust and has no positions in the stocks mentioned.

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