Investing isn't easy. Even Warren Buffett counsels that most investors should invest in a low-cost index like the S&P 500. That way, "you'll be buying into a wonderful industry, which in effect is all of American industry," he says.

But there are, of course, companies whose long-term fortunes differ substantially from the index. In this series, we look at how members of the S&P 500 have performed compared with the index itself.

Step on up, 3M (NYSE: MMM).

3M shares have handily outperformed the S&P 500 over the last three decades:

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Source: S&P Capital IQ.

Since 1980, shares returned an average of 12.3% a year, compared with 11.1% a year for the S&P (both include dividends). That difference adds up fast. One thousand dollars invested in the S&P in 1980 would be worth $29,400 today. In 3M, it'd be worth $40,900.

Dividends accounted for a lot of that gain. Compounded since 1980, dividends have made up 66.3% of 3M's total returns. For the S&P, dividends account for 41.5% of total returns.

And now have a look at how 3M's earnings compare with S&P 500 earnings:

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Source: S&P Capital IQ.

Again, pretty solid outperformance. Since 1995, 3M's earnings per share have grown by an average of 7.5% a year, compared with 6% a year for the broader index. That's testament to the power of the company's brand, strong international growth, and smart management that has pieced together its conglomerate operations without losing focus.  

But, perhaps oddly, that earnings-growth dynamic hasn't led to superior valuations. 3M has traded for an average of 20.8 times earnings since 1980, compared with 21.3 times for the S&P.

Still, the company has been an above-average performer historically.

The question is whether that can continue. That's where you come in. Our CAPS community currently ranks 3M with a five-star rating (out of five). Do you disagree? Leave your thoughts in the comment section below, or add 3M to My Watchlist.