By Eric Dutram of ETF DatabaseAlthough the ETF world started by focusing on tracking well known indices such as the S&P 500, it has significantly branched out in recent years, offering funds that track everything from commodity indices to quantitative methodologies that attempt to deliver excess returns. These quant ETFs haven't really hit it big yet, but they have certainly attracted a fair amount of assets from investors who believe in the benefits of stock analysis but are eager to reap the benefits of the ETF structure. One interesting marriage is found in the PowerShares DWA Technical Leaders Portfolio ( PDP), a fund that offers access to a strategy of buying and selling securities based on chart patterns and other technical indicators such as relative strength levels. Investors who emphasize relative strength believe that stocks that show high relative strength compared with broader indexes are likely to continue increasing in price, and that it is better to buy those stocks than to buy stocks with falling prices. In other words, "