Prospective or retrospective. What's the right choice for your strategy?

Prospective, or predictive, strategies attempt to predict future price movements and allocates holdings according to what is expected to happen - all in search of alpha, or above market returns.

Retrospective strategies look at what has happened in the belief that part trends are indicative of future trends, and allocates holdings to what has performed well historically - in an attempt to generate stable income or returns.

So which is best? Of course it depends on your risk appetite, market outlook, investing approach and goals. However these are two very different approaches, and a while a retrospective strategy can be purely analytical a predictive strategy necessarily involves extrapolation which intuitively seems more risky.