I’d need to do a Monte Carlo to provide hard evidence but I’m fairly sure that lump sum investing is, on average, going to provide the greatest return. For people just starting out in investment, whose appetite for risk is high, that seems the way to go.

Edit: Leggio and Lien (2001):

> We find DCA [dollar-cost averaging] consistently remains an inferior investing strategy to Lump Sum investing using the risk-adjusted performance measures.

> The failure of DCA as an optimal investing strategy for all assets and portfolios considered is likely because DCA is a conservative investing strategy best suited for investors interested in a forced savings plan that avoids the consumption of earnings.