When it comes to exchange traded funds (ETFs), investment strategy can make all the difference.

Since the year is past the halfway mark, it is fair game to start comparing ETFs within the same sector, and ETFGuide compares three funds which track commodities. The commodities sector has been the one of the most successful for 2008, but the three funds are delivering different results.

iShares S&P GSCI Commodity Indexed Trust (GSG) is up 44.8% and uses a passive method for selecting commodities. GSG weights upon world production, measuring the average production over the past five years.

PowerShares DB Commodity Index (DBC) is up 47.1% and has a different process for selecting and weighting which commodities are tracked on the DB Liquid Commodity Index-Optimum Yield Excess Return Index. DBC is composed of futures contracts on six commodities, with 55% toward energy commodities, using a modified equal-weighting strategy.

GreenHaven Continuous Commodity Index (GCC) is up 21.9%, and uses the same passive method for selecting commodities as GSG. GCC follows the Continuous Commodity Index Total Return, an equally-weighted basket of 17 commodities.

As a consumer, the commodities boom can make you feel pinched, but the bull market of raw materials is a tremendous investment opportunity.

So why start now and incorporate commodities into your portfolio? There are two reasons that Brian O’Keefe for Forbes believes putting your money into resource markets can get you ahead.

For one, the current highs are representing a market top, but are not actually the peak, according to Jim Rogers. Even if a short-term correction were to occur, the bull market still has a long way to go.

Another reason to add commodities to your portfolio mix is that some experts suggest that they seem to offset inflation. For both of these reasons, a growing number of planners and advisors are putting 5-10% of a portfolio into commodities. It’s a new wave and some say it isn’t overly aggressive to propose a 10% allocation at this point. However, it all depends on your preference.

The opinions and forecasts expressed herein are solely those of Tom Lydon, and may not actually come to pass. Information on this site should not be used or construed as an offer to sell, a solicitation of an offer to buy, or a recommendation for any product.