It is pretty well proven that DCA is historically sub-optimal statistically. That is simply because the market has a positive long term bias. So if you had $x and wanted to invest it over time, chances are, you would have been better off if you had put it in lumpsum at the start of the period vs. DCA over the entire duration of the period.
If the time horizon was, say 10 years, or 20 years, or any long enough period where the market has historically had a positive return, you were better off doing lump sum. In the few periods when the market had a negative return during that time, then you were better off doing DCA.
In short term time spans of 1 or 2 years, lump sum investing still won out more often than DCA, but because negative return 1 year periods are more frequent than negative return 10 year periods, if your investment horizon is shorter term, you may be psychologically better off doing DCA. There's a mental saving grace of "at least I bought some stock when prices were low" and that's what people want to be able to say. If they bought lump sum and the market then tanked right after, people have a lot of regrets. And losing money they had is harder on people than not making potential money they may have made IF they had invested.
In the end, it may be better to DCA for you because it's sort of hedging your bets. I would say, if you knew that the market was going to tank, you should short the market and leverage it as much as you can. But we all know that no one knows exactly what the market will do. So given that you want to invest your money BUT you are scared that it will tank (just like everyone else) you may be better off doing a DCA investing over how many ever periods that you'd like. Maybe over a 2 year period, while keeping the funds in a savings account? (I just opened up a GE Capital one which gives 0.95% interest. Better than nothing). Or you can buy treasuries in a ladder fashion to mature in various time periods (3 months, 6 months, 9 months, 1 year, etc.). And whenever it matures, you then put it into whatever index fund you want to invest in.