When evaluating mutual funds, we often spend a lot of time looking at past performance. The assumption is that a fund which has performed well in the past, will continue to perform well in the future. We tend to assume that this past performance was due largely to the skill of the manager running the fund. But how do you distinguish between skill and luck? Can a fund perform well in a number of consecutive years purely as a result of luck?
The short answer is, yes. Statistically speaking, it’s entirely possible that a fund manager could have a winning streak that lasts several years, due in large part to luck.
I read a story somewhere ( I can’t remember where now) about a finance teacher who used to impress this point upon his students with a simple exercise. Everyone in the class would stand up. The teacher would then toss a coin, and the students would call it. Everyone who got the call wrong would sit down. Inevitably, with each toss, a large portion of the class would sit down. But there would always be a few individuals who remained standing for a long time, and one would often outlast them all, correctly calling ten to twenty coin tosses, or more.
What this illustrates is that it’s statistically possible for a mutual fund manager to have a series of consecutive winning years which are attributable in whole, or in part, to luck. Determining whether performance is attributable to luck or skill is next to impossible in the short term. When a fund has a good year, the management can point to all the decisions they made, and seem prescient, as if they knew all along what was going to happen in the market. When things don’t go so well, they can point to “unforeseen factors” which adversely affected returns. We might forgive them their failure because, after all, even the best can’t be right all the time.
But skill can’t be discounted entirely. Calling coin tosses doesn’t involve any skill at all, so it’s actually not an entirely fair comparison to stock picking. If I stood in front of a basketball hoop, there’s a statistical chance that I could make twenty free throws in a row. I would venture a guess that the odds are somewhere near one in a million, but it’s possible. If Michael Jordan were standing in front of the hoop, the odds of twenty baskets in a row would be a lot better.
Similarly, knowledge of the markets, economic trends, accounting, and company management, are all special skills that will give a fund manager an edge in picking stocks over a complete amateur. However, the difficulty is, picking stocks isn’t like making free throws. Picture Michael Jordan in front of a basket that moved in a random direction every few seconds, and you’ve got a good idea of what a fund manager is up against.
So what do you do as a mutual fund investor then? Well, one solution might be to hedge your bets, and put the greater portion of your stock investment money into an index fund which passively tracks the entire market. You will never outperform the market, but you won’t significantly underperform it either. If you must pick an actively managed mutual fund, the best you can do is to look for a track record of superior performance, and hope that the greater part of that performance was due to luck, and not to skill.