The Role of Luck and Skill in Investing
Michael Mauboussin is head of Global Financial Strategies at Credit Suisse and the author of several books, including “The Success Equation: Untangling Skill and Luck in Business, Sports, and Investing (Harvard Business Review Press, 2012). He and I spoke about the role skill and luck play in investing.
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Charles Rotblut (CR): A big theme in your recent book is the distinction between skill and luck. Could you explain what the difference between the two is?
Michael Mauboussin (MM): One of the ways I like to think about this is as a continuum of activities from pure luck and no skill on one end to pure skill and no luck on the other end [Figure 1]. Obviously, most things reside somewhere between the extremes, and where an activity sits can be very important. But before we get going, it is important to define the terms.
I’m going to define skill right out of the dictionary: The ability to apply one’s knowledge readily in execution or performance. You know how to do something, and when you’re asked to do it, you can do it effectively.
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Luck is much more difficult to define. It actually spills into moral philosophy pretty quickly. I’m going to say that luck exists when three conditions are in place. Number one, it operates on an individual or an organizational basis, such as you or your team or company. Second, it could be good or bad. By that, I don’t mean to suggest that it is symmetrical, as in it could be equally good or bad. But rather there is a plus sign or a minus sign. The third thing is that it is reasonable to expect that a different outcome could have occurred. If those three things apply, then you’re in a situation where luck exists.
Not surprisingly, when you look out into the world, whether it’s business, investing or your favorite sports team, both skill and luck are contributing. The real question is, in what proportion?
CR: Do you think investors confuse the two when looking at their own performance, in that they think they are skillful when they have actually gotten lucky?
MM: There is actually a very interesting test to determine if there is any skill in an activity, and that is to ask if you can lose on purpose. If you can lose on purpose, then there is some sort of skill. Investing is very interesting because it is difficult to build a portfolio that does a lot better than the benchmark. But it is also actually very hard, given the parameters, to build a portfolio that does a lot worse than the benchmark. What that tells you is that investing is pretty far over to the luck side of the continuum. That is the first important thing.
The second thing is that luck is a very difficult thing for us to deal with psychologically. The main reason has to do with a part of your brain in the left hemisphere. If you give it any effect, it will immediately and effortlessly come up with a cause. That part of your brain knows nothing about luck. It only knows about causality. So it attaches skill to positive outcomes and it attaches lack of skill or maybe bad luck to poor or negative outcomes. So there is this kind of disconnect between what happens in the real world and how our mind interprets those events. And to your question, we tend to associate good outcomes with good skill alone and that’s often simply not the case. And bad outcomes are not necessarily associated with bad skill either. It’s a very tricky relationship to understand clearly.
CR: If someone is following a set process of picking stocks or bonds and it doesn’t do well, is this a case where the investor should look at how the strategy has performed in the past and if it has worked well, just attribute the poor performance to luck turning against them?
MM: For sure. Part of what I talk about in the latter part of the book is how to improve one’s skill. What I argue is that when you’re on the skill side of the continuum, your output and your skill are very closely related to one another. If I want to know if you’re a good violin player or a good tennis player, I can listen to you or watch you play and I can tell quite quickly. When you move over to the luck side, it becomes process-oriented and probabilistic. For example, there is a standard strategy for blackjack. You may play your cards properly and lose the hand, which is just bad luck, or you may play your cards foolishly and win the hand. So the connection between the quality of your skill and the outcome is broken. There, you really have to focus on process.
How do I know if my process is any good? Number one, has it worked in the past and is it economically sound? Number two, I think of good processes as having three essential elements. Element one is analytical: having an ability to find situations in which you believe something the world doesn’t believe and in which you have a good foundation for such a belief. The second is behavioral: we are all subject to behavioral mistakes and cognitive biases. Are you aware of those things and are you taking steps to manage or mitigate them? The third, which is less true for individuals and truer for organizations, is what I call institutional. This element relates to the constraints in your personal or professional life that don’t allow you to do the best thing possible in terms of your process. If you have a good analytical process, are aware of behavioral issues and organizational issues are not a problem, then you typically can develop a pretty effective process. If you’ve done that and you get a bad outcome in the short term, you pick yourself up, dust yourself off and you go back at it the next day because over time the process will lead to success.
Michael Mauboussin is head of Global Financial Strategies at Credit Suisse and the author of several books, including “The Success Equation: Untangling Skill and Luck in Business, Sports, and Investing” (Harvard Business Review Press, 2012).