Yes you could, sort of. Good, basic investing isn’t rocket science, but even so, most people don’t do it nearly as well on their own.

To cite the hard evidence, since 1994, financial market research firm DALBAR has released an annual update on its Qualitative Analysis of Investor Behavior (QAIB), indicating that investors significantly underperform the very investments they hold. According to the most recent QAIB, covering 20 years of data through 2010, investors earned just under 4 percent compared to S&P 500 returns of just over 9 percent. That’s a lot of wealth left on the table.

DALBAR and many other studies demonstrate that investors’ inability to capture available returns is a self-inflicted wound that results from over-active trading. In the absence of careful planning and disciplined, long-term strategy, our natural tendencies are to react to emotions rather than adhere to strategy, which results in buying and selling at the wrong times, for the wrong reasons.

Our primary role is to ensure that you stick to your well-built plan over time and across volatile markets. If circumstances change then the plan must change. This may sound like no big deal; but there is clear evidence that individual investors lack the resolve to go it alone.