i think most of the research stats are based on longer term than 5 years - 10s of years or rolling 20 to 30 years.
"Knowing" that equities goes up in time, IF one has say $100K, the stats are for the lump sum investment instead of breaking it up to do DCA for RETURNS purposes.
DCA in above situation is more for psychological acceptance / "staying power" (ie. not run helter skelter).
However, in normal terms where we dont have $100K lump sum every year or three, then DCA, VCA or value hunting makes more sense coz if we just hold and time, bila nak masuk?
http://www.investopedia.com/articles/stocks/07/dca-fight.asp...
DCA Vs. Lump-Sum Investing
Both lump-sum investing and DCA have their appropriate time and place. The research shows that lump-sum investing pays off about 66% of the time, which is a long way from all the time. It certainly makes sense to look carefully at the current market conditions. If you hit that bad 33% in lumpy style, you can lose a lot of money.
On the other hand, many DCA users fail to monitor their investments after they start. The mere fact that you are investing in small pieces does not mean that you don't need to rebalance your portfolio, watch for changes in fund managers or in the economic environment, etc. So part of the problem is not DCA itself, but the fact that other investment issues still have to be taken care of. Indeed, one broker refers to the "no-brainer DCA", the equivalent of Smyth's "blind DCA".
Conclusions
DCA does not provide any real kind of guaranteed return and/or risk reduction. And it certainly does not work well in all market situations. Furthermore, research in the area indicates that lump-sum investing tends to perform better over the longer term.
Nonetheless, DCA is far less nerve-wracking than a lump-sum investment, and if there is a major bear market around the corner, it can really pay off. In some situations, it is an ideal way of controlling both risk and stress.
You can also treat DCA as just one of the strategies that you use in your overall portfolio (in other words, it makes sense to use it as a form of diversification), but as with those other strategies, you still need to monitor, manage and rebalance your DCA investments. (Read more about diversification and balance in Risk And Diversification and Rebalance Your Portfolio To Stay On Track.)
Finally, regular investing is a lot better than no investing at all. If the choice is between putting away $50 a month or treating yourself to an extra night on the town, it is clear which option will see you through your old age.
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http://www.bogleheads.org/wiki/Dollar_cost_averaging...
When you are ready to invest money, a common question is whether you should invest it as a lump sum or Dollar Cost Average (DCA) by splitting your investment across several payments. The answer depends on your psychology.
In most cases, you are moving your money from cash (or the equivalent, a low-yielding money market) to some mix of stocks and bonds. The expected value of both stocks and bonds are higher than cash. However, their volatility is higher as well. The risk is that just after making your investment, the market could crash, causing you to feel bad that you invested when you did.
Of course, according to Bogleheads Investment Philosophy, you should only be investing in the first place into a diversified asset allocation. Also, you should only be holding volatile funds like stocks and bonds if your investing horizon is long enough to ride out their volatility.
For a completely rational investor, lump sum investing will always produce a higher expected return, because it immediately moves your funds from asset classes with lower expected returns to ones with higher expected returns. Note that higher expected returns do not guarantee that your actual returns will be higher. According to an investopedia article, [6] studies indicate that lump sum investing has produced higher returns 66% of the time.
Some investors have the goal, not of maximizing their expected returns, but of minimizing their potential regret. For those investors, dollar cost averaging is superior because it reduces the chances of investing just prior to a market drop. If you instead decide to invest 1/6th of the money each month for 6 months, you will reduce the chance of buying just before a crash. Instead, as the price fluctuates each month, you will buy more shares when the price is low and less when it is high.
Many new investors are more interested in minimizing their potential regret, and it's important that an ill-timed market drop not scare them off from investing in the future. Many experienced investors are more interested in maximizing their expected returns. You can also decide to split the difference, where you invest half immediately and the other half over 6 or so months.
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never really thought that lump sum investment would yield better return in the long term, i would consider it then