This week I received some odd communications from mutual fund giant Vanguard Group.

First, they sent a white paper titled, “Here today, gone tomorrow: The impact of economic surprises on asset returns.” As the title suggests, this paper examined the relationship between the economy and the stock market. In particular, they asked whether accurate economic forecasts could help an active trader profit in the stock market. Their conclusion: An investor’s predictions would need to be accurate 75% of the time in order to beat a simple buy-and-hold strategy. Then they address the question that logically follows: “How achievable is a 75% success rate?” The paper’s answer: “Not very.”

That was the first paper—and the conclusion seemed entirely logical: Don’t bother with your crystal ball; it’s highly unlikely to help you beat the market.

Then the second paper came. The title of this one: “Vanguard market and economic outlook for 2019.” In this paper, the authors provide their outlook on a variety of topics: economic growth, inflation, unemployment, and much more. The paper runs more than 40 pages, with probabilities placed on a variety of events. For example, they foresee an 18% chance that the U.S.-China trade war escalates and a 29% chance that the two countries reach an agreement.

In other words, the second paper was full of the sorts of economic predictions that, in the view of the first paper, are largely “irrelevant.”

What’s going on here? Vanguard’s first paper made perfect sense. Why did they invest so much time assembling that second one, one that, in their colleagues’ own estimation, is unlikely to help investors?

I don’t mean to single out Vanguard. At this time of year, all the big financial firms are busy issuing forecasts. Morgan Stanley sees corporate profits slowing next year and the potential for a technical recession. Credit Suisse sees the S&P 500 rising to 3,350 next year. And Wells Fargo projects S&P 500 profits at precisely $173.37 per share.

In short, everyone has an opinion. So is it possible that Vanguard’s first paper—the one skeptical of predictions—was the one that was wrong? If all of these major institutions spend so much time formulating and publishing their forecasts, maybe they are worthwhile after all?

Economist Prakash Loungani has spent the better part of two decades researching this question. In a 2001 study, Loungani evaluated experts’ ability to forecast recessions. His conclusion was blunt: “The record of failure to predict recessions is virtually unblemished.” In a follow-up study, looking at the 2008 financial crisis, Loungani’s findings were nearly identical. Economists uniformly failed to predict that global recession.

Perhaps Loungani’s study wasn’t comprehensive enough? Certainly there are all-stars in every field. What about the all-star forecasters? Here, the evidence is necessarily more anecdotal, but no more encouraging. Consider Abby Joseph Cohen, the recently-retired Goldman Sachs strategist. Her forecasts during the 1990s earned her the nickname “The Prophet of Wall Street.” But she later missed the two biggest meltdowns of her career: In 2000, when the dot-com bubble burst, Cohen predicted that the market would rise. And she (along with virtually everyone else) missed the 2008 collapse.

A more recent example: Ray Dalio, the billionaire founder of hedge fund Bridgewater Associates, proclaimed in January of this year: “If you’re holding cash, you’re going to feel pretty stupid.” The year’s not over yet, but so far, cash has done materially better than the stock market, which is in negative territory.

The reality is that forecasting has always been difficult—and not just in the world of economics. Decca Records told the Beatles they have “no future in show business.” Walt Disney was once fired for “lacking imagination.” The list of incorrect predictions is long.

But if forecasts are so error-prone, why do sensible organizations like Vanguard continue issuing them? In part, I believe it’s in response to investor demand: People want to know what’s going to happen, and they want an expert to tell them. It’s just human nature, and it’s understandable. But now that you’ve seen the data, my recommendation would be to tune out anyone who approaches you with a crystal ball. Instead, to the greatest extent possible, situate yourself so that the market’s regular ups and downs don’t impact your ability to meet your financial goals—or to sleep at night—when 2019 rolls around.