When it comes to either the free fall or sudden surge of the stock market, I can’t help but think of that song by The Clash:

“Should I Stay or Should I Go.”

One part of the song is quite relevant, given these turbulent investment times. “If I go there will be trouble. An’ if I stay it will be double.”

Like all hot but tormented love affairs, there comes a time when you have to ask that question. Should I stay or should I go now? In this case, should you sell your individual stocks or shares in your stock mutual fund?

Truth is, I can’t answer that for you. But I will say this: I’m not afraid of what’s been happening in the market. I need to be in the stock market. And I’m staying put because I have a plan.

People are panicking and jumping out of stocks because they don’t have an investment strategy, said Yvonne Bass, a Maryland-based financial adviser with American Express.

“Too many people look at one area, and they don’t look at the others,” Bass said.

Added James R. Cotto, a financial planner based in Mount Kisco, N.Y.: “It’s a tough time for all of us, and absence of a plan is what leads to anxiety, and that will lead you to make an emotional decision instead of a financially prudent one.”

So if you want to stay, what should you do?

One word diversify.

Diversification means having a mix of investments in different sectors or industries. A well-diversified portfolio might include bonds, money market funds and stocks of small, medium and large companies in a variety of industries and countries.

Because many investors don’t really understand the concept of diversification, the nonprofit Alliance for Investor Education has put together a list of Web sites with basic information on how to diversify your portfolio. Go to www.investoreducation.org and click on “Diversification 101.”

There’s something else to consider if you decide to stay with stocks. Base your investment decisions on unbiased research. One newly formed nonprofit organization Investorside Research Assn. hopes to help individuals find their way to more independent research on the companies they want to invest in. The organization’s mission is to give a gold seal of approval to companies that aren’t involved in investment banking. Its Web site is www.investorside.org.

Learning to diversify and getting your hands on independent research is all well and good, but what if you just can’t stand the fickle nature of the stock market? What if you just want to go?

For those who want to get out of equities, Cotto said he recommended buying very short-term treasuries, high-grade corporate bonds and certificates of deposit.

Cotto said he recommended buying short-term three to five years because if interest rates rise, you don’t want to be holding long-term fixed income instruments in a rising interest rate environment.

“As interest rates rise, the value of your bonds will go down because the government and corporations are issuing debt at those new higher rates,” Cotto said.

Ultimately, whatever you decide to do stay or go make sure you’re thinking with your head and not your heart.