Three Landmines

Adam M. Grossman

SCOTT ADAMS, the creator of Dilbert, has this to say about making forecasts: “There are many methods for predicting the future. For example, you can read horoscopes, tea leaves, tarot cards, or crystal balls. Collectively, these methods are known as ‘nutty methods.’ Or you can put well-researched facts into sophisticated computer models, more commonly referred to as a complete waste of time.”

This is funny but, for the most part, I agree. It’s especially true in the world of investments. And yet, as you manage your financial life, some amount of forecasting is unavoidable. Anyone trying to build a retirement plan, for example, has to think about future market returns, interest rates, inflation and taxes. All of these factors—and others—will have an enormous impact on our financial future, so we need to make some estimates.

If forecasting is a necessary evil, it’s important to understand it—flaws and all. Daniel Kahneman, a founding father of behavioral finance, provides a useful framework. The first thing to understand about forecasts, he says, is that there are three factors that can cause them to go awry: incorrect or incomplete information, biases and noise.

1. Information. This one might seem self-explanatory. After all, the fundamental problem with any prediction is that it’s impossible to know what will happen in the future. That seems obvious. But for investors, it isn’t so simple. The reality is, there’s a lot of information that could help us make predictions. But sometimes that information is flawed, incomplete or irrelevant. As an example, you may recall the 1983 movie Trading Places.

In that film, a group of investors was betting on commodities—specifically, frozen orange juice. The prevailing wisdom was that a cold winter had hurt the orange harvest and would result in higher orange prices that year. But in the end, it turned out that the cold weather hadn’t had much of an impact. The harvest was fine and prices moved in the opposite direction from most investors’ expectations. In other words, investors were right about the weather but lacked information on the harvest itself. They only had one piece of the puzzle. To be sure, this is a fictional example, but this kind of thing happens all the time. As an investor, you need information that’s both reliable and complete.

We saw the same sort of effect in 2020. When the coronavirus shut down the economy, it was clear it would impact corporate earnings and thus stock prices. But no one knew precisely how things would turn out—which companies would be hurt, which would benefit and how long it would last. Again, we had a lot of information, but still there were a lot of holes.

2. Biases. When we talk about errors in investment forecasting, what we’re usually talking about are biases. When we lack information, that’s a problem that is largely out of our control. But biases are problems we cause ourselves. Biases refer to the way we use the information we have. Even in situations with perfect information, biases cause people to interpret that information differently or to cherry pick the information they wish to include.

We see investor biases around presidential elections, for example. Each candidate’s platform is usually pretty clear. Where investors differ, however, is in how they expect those policies to affect markets.

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Kahneman’s book Thinking, Fast and Slow discusses biases—including investing biases—in detail. It’s a book I recommend.

3. Noise. In behavioral finance, biases get most of the attention. But Kahneman believes noise is an underrated contributor to investment forecasting. What is noise exactly? In short, it’s randomness in human thinking and behavior. Whereas biases have a logical basis—even if that basis is flawed—noise has no underlying logic at all. In Kahneman’s research, he’s found a surprising amount of noise in the world. Professionals as diverse as physicians, insurance adjusters and software developers all exhibit noise in their work.

What does it mean to exhibit noise? As an example, Kahneman cites pathologists making two assessments of the same biopsy. The correlation between two assessments by the same pathologist was, on average, just 60%. In other words, the same pathologist looking at the same data came to a different conclusion 40% of the time—for no clear reason.

Kahneman found the same thing across other professions and industries, including finance. “The problem,” Kahneman explains, “is that humans are unreliable decision makers; their judgments are strongly influenced by irrelevant factors, such as their current mood, the time since their last meal, and the weather.”

As an investor, how can you protect yourself—and your finances—from the landmines of bad information, bias and noise? Drawing on Kahneman’s work, as well as that of Philip Tetlock, co-author of Superforecasting, here are five recommendations:

  • Consider the forecaster’s track record. Just because you see pundits speaking on TV or quoted in the news doesn’t mean that their track record has been vetted. If they have a public platform, their track record should be public as well, allowing you to judge it for yourself.
  • Evaluate a forecaster’s methodology. Is he or she relying on facts and data or on intuition and stories? Is the forecast based on simple extrapolation or is there a more logical basis? Again, don’t assume that everyone with a public platform is doing things logically.
  • Consult multiple sources. Don’t rely on just one forecast. This can help lessen the impact of noise. As Kahneman noted, people’s views are often inconsistent with their own prior judgments, so judgments will certainly differ from person to person.
  • To the extent possible, structure your portfolio to be “all weather,” so you’ll be okay regardless of how the future turns out. In other words, don’t set your finances up to be overly wedded to—and thus overly exposed to—one particular version of the future. That will give you the freedom to largely ignore the constant din of investment narrative coming out of Wall Street.
  • Try to remove judgment from your investment process whenever possible. I always recommend a written investment policy, for example, including a target asset allocation and rules for rebalancing.

Adam M. Grossman is the founder of Mayport, a fixed-fee wealth management firm. In his series of free e-books, he advocates an evidence-based approach to personal finance. Follow Adam on Twitter @AdamMGrossman and check out his earlier articles.

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2 years ago

Best is to follow the sage advice of Yogi Berra: ‘It’s tough to make predictions, especially about the future’”

You state, correctly: “… Anyone trying to build a retirement plan, for example, has to think about future market returns, interest rates, inflation and taxes. All of these factors—and others—will have an enormous impact on our financial future, so we need to make some estimates. …”

But, I don’t believe in adopting a specific plan for “retirement”. Gainful employment will end at some future date – perhaps due to disability, death, caregiving responsibilities, involuntary termination/job loss, or personal decision.

Even though I’ve been part of the employee benefits industry for the past 42 years, more than once I excised the word “retirement” from 401k and defined benefit plan education and marketing materials. Instead, I’ve adopted themes like:

  • “Drive to your dreams … whatever you may be dreaming about, and
  • “Will you be a middle class 401k millionaire, … someday?” .

Two favorite quotes from my planning seminars of the past:

  • “Plan to live, because death will take care of itself.”
  • “Life is not a dress rehearsal for retirement, start doing some of things you’ve been dreaming about”
2 years ago

Great article, as usual. I am a big fan of Daniel Kahneman, and also another (organizational) psychologist Adam Grant. Daniel Kaheman just recently got interviewed by Adam Grant in Grant’s podcast “WorkLife”. It is quite amazing to see two personal heros discussing about decision making and intution, etc

Rick Connor
Rick Connor
2 years ago

Great article Adam. Thinking, Fast and Slow is one of my favorite books. I spent 40 years creating and executing predictive models of complex physical systems. For these systems, the physics was generally well understood. But the models, and results, all suffered from the 3 items above. In these kinds of systems, engineering judgment helped #1 &2, but could be the case of bias. Compared to deterministic physical systems, complex systems involving human interactions are basically non-deterministic. I have very little faith in short term financial projections.

Roboticus Aquarius
Roboticus Aquarius
2 years ago

Every summer I forecast the price of a barrel of Brent Crude for the next year. I look at the bank forecasts; I look at Industry forecasts; I look at the NY Merc Futures; I look at the EIA information – aged as it is. I look at estimates of production and distribution, assess the US shale fields and their impact as well. Yet, I always return to the decade+ old U of Michigan study on such predictions. The publishers concluded that the most accurate forecast methodology was to assume no change in price.

Sometimes, nobody has much of a clue. It’s best if we just admit it and stop trying to predict the unknowable.

Last edited 2 years ago by Roboticus Aquarius
2 years ago

The big problem is that unexpected things are always happening.
OK, we just had the corona-virus. Now we have the vaccine, so everything is good, right?
Well, maybe interest rates will go up sharply for no obvious reason, maybe China will invade Taiwan, maybe the hedge funds will all collapse and crash the market.
As a retiree, I have to be ready for any possible scenario.

Mr Moderate
Mr Moderate
2 years ago

Wonderful points! I’ve been guilty of #3 Noise. Hopefully get juries and judges that are happily married and well-fed!

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