Alcoa (NYSE:AA) has many roles: Aluminum giant. Materials stock. Dow component. Blue-chip stalwart.

Four times a year, it’s also an “earnings bellwether” — a silly moniker that InvestorPlace contributor James Brumley aptly tore apart the last time earnings season came around. And with Alcoa reporting earnings yesterday after the bell, the time is ripe to consider dethroning Alcoa as some sort of broader materials bellwether — especially as far as the Select Sector Materials SPDR (NYSE:XLB) is concerned.

The first argument against is right on XLB’s face: Alcoa is a poor representative of the ETF to begin with. Chemicals companies DuPont (NYSE:DD) and Dow Chemical (NYSE:DOW) make up roughly 20% of XLB’s holdings, and seed/chemicals firm Monsanto (NYSE:MON) accounts for another 10.5%. Alcoa? A piddling 2.3%.

XLB does include other mining and metals operations, but Alcoa’s more or less floating on a small aluminum boat.

But a look a quick look at Alcoa’s earnings results, post-earnings action and what AA does between quarterly reports shows there’s no meaningful connection between the performance of AA and XLB. (And while it’s not included in the table below, day-after returns for XLB don’t show much correlation, either.)

Ergo, the fact that Alcoa turned out a Q2 loss, or however AA finishes out Tuesday’s trading … well, don’t project any of it onto XLB.

Alcoa’s and aluminum’s issues are all their own, as evidenced by the performance of several of XLB’s components — DD is up 40% since Jan. 1, 2010, and DOW is up 12% — in the same time frame.

In fairness, though, the connection many perceive between the two isn’t outright silly. One of the biggest arguments for believing in Alcoa is that it’s a bet on economic recovery. You can make the exact same statement for XLB. If the world is growing, it’s using paints, it’s planting seeds, it’s installing copper pipes in houses — and it’s manufacturing aluminum into about a thousand different things.

And that leads me to something else you should take out of this data.

If you want to make a directional bet on a broader idea — in this case, economic recovery — sure, you can ride Alcoa in the hopes that a global revival sparks aluminum demand along the way. But at the end of the day, you’re still making a specific bet on a specific company in a specific business.

However, ETFs — especially sector funds like the XLB and others — let you make that broad call across a broader spectrum of companies. Yes, you’ll likely give up single-stock jumps like AA’s 30% gains in late 2010, but you’ll also often avoid those 20%, 30% and 40% dips.

Or more succinctly, the highs won’t be as high, but the lows won’t be so low.

So my advice? If you think there’s a bottom in aluminum prices and that Alcoa has right-sized itself into a lean, mean rebound machine, go long AA and don’t look back.

But if you plain-old think that the global economy is getting ready to right the ship, don’t take more risk than necessary — pile into XLB and let the whole gang do the talking.

Kyle Woodley is the Assistant Editor of InvestorPlace.com. As of this writing, he did not hold a position in any of the aforementioned securities. Follow him on Twitter at @KyleWoodley.