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Should we rely on economic forecasts? The wisdom of the crowds and the consensus forecast

16 January 2017
by Guest author

Brian Dowd, FocusEconomics

Laurence J. Peter, a Canadian educator and author, is often referenced as saying, “an economist is an expert who will know tomorrow why the things he predicted yesterday didn’t happen today.”

Economics and especially economic forecasting are often given a bad rap. Many people think of forecasting as akin to licking a finger and testing the wind. However, there is a science to it.

Forecasting is essentially attempting to predict the future and predicting the future behavior of anything, much less something as complex and enormous as an entire economy, is not an easy task, to say the least. Accurate forecasts, therefore, are often in short supply.

There are a few reasons for this; the first being that economies are in perpetual motion and therefore extrapolating behaviors and relationships from past economic cycles into the next one is, as one might imagine, tremendously complicated.

The second reason, and perhaps the most surprising, has to do with the vast amount of raw economic data available. In an ideal world, economic forecasts would consider all of the information available. In the real world, however, that is nearly impossible, as information is scattered in myriad news articles, press releases, government communications, along with the aforementioned mountain of raw data.

Although some might consider having all of that information an advantage, nothing could be further from the truth. The thousands of economic indicators and data available tend to produce a vast amount of statistical noise, making the establishment of meaningful relations of causation between variables a serious challenge.

And, of course, we cannot forget the uncertainty that is inherent with forecasting, something that forecasters must take into account and which creates even more noise to deal with.

The question then becomes, is there a way to cancel out all of that noise to get a more accurate forecast? This is where the wisdom of the crowds comes in.

Is there wisdom in the crowds?

To illustrate how the wisdom of the crowds works, it’s best to tell the story of Sir Francis Galton, a Victorian polymath, who was the first to note the wisdom of the crowds at a livestock fair he visited in 1906. In one event, fairgoers were given the opportunity to guess the weight of an ox. The person with the closest guess to the actual weight would win a prize.

Galton hypothesized that not one person would get the answer right, but that everyone would get it right. Bear with me.

Over 750 participants made their guesses and unsurprisingly no one guessed the weight perfectly. However, when Galton calculated the mean average of all of the guesses, incredibly, it turned out to be the exact weight of the ox: 1,198 pounds.

Tapping economic analysts’ wisdom with consensus forecasts

The basic idea of the wisdom of the crowds is that the average of the answers of a group of individuals is often more accurate than the answer of any one individual expert. This was evident in the story of Galton’s experiment at the fair.

For the wisdom of the crowds to be more accurate, it depends on the number of participants and the diversity of the expertise of each individual participant. The more participants involved and the more diverse the participants are, the lower the margin of error.

So what does the wisdom of the crowds have to do with economic forecasting? Remember all of that noise that makes economic forecasting so difficult and as a result affects the accuracy of forecasts? The theory is that idiosyncratic noise is associated with any one individual answer and by taking the average of multiple answers, the noise tends to cancel itself out, presenting a far more accurate picture of the situation.

Sometimes also referred to as simply combining forecasts, the consensus forecast borrows from the same idea of Galton’s wisdom of the crowds – a consensus forecast is essentially the average of forecasts from various sources. Averaging multiple forecasts cancels out the statistical noise to yield a more accurate forecast.

But don’t take my word for it. Over the last few decades there has been a great deal of empirical research that has shown consensus forecasts to increase forecast accuracy, including those cited below.

With that said, it is possible for an individual forecast to beat the Consensus, however, it is unlikely that the same forecaster will consistently do so one forecast period after another. Moreover, those Individual forecasts that do happen to beat the consensus in one period are impossible to pick out ahead of time since they vary significantly from period to period.

Taking a look at a practical example may serve to clear things up a bit further.

A practical example of a consensus forecast

In the graph above, the Consensus Forecast for Malaysia’s 2015 GDP taken in January 2015 was 5.1%. All the other points, marked in grey, along the same axis represent the individual forecasts from 25 prominent sources taken at the same time.

In March 2016, the actual reading came out at 5.0%. A few forecasts were closer to the end result, however, as mentioned previously, some individual forecasts are going to beat the consensus from time to time, but it won’t happen consistently and it would be impossible to know which forecasts those will be until after the fact.

The second graph uses the same example as before; 25 different economic analysts forecasted Malaysia’s 2015 GDP in January of 2015. By March 2016, the maximum forecast turned out to be 16% above the actual reading with the minimum 10% below the actual reading.  The consensus was only 1.9% above the actual reading. By taking the average of all forecasts, the upside and downside errors of the different forecasts mostly cancelled each other out. As a result, the consensus forecast was much closer to the actual reading than the majority of the individual forecasts.

Consistency and reducing the margin of error are key

The point to keep in mind is that whether they are consensus forecasts or individual forecasts or any other kind of forecast, predicting the future is seldom going to be perfect. In the Malaysia GDP example, the Consensus wasn’t spot on, but it did certainly reduce the margin of error. It is important to note that there is almost always going to be some error, but reducing that error is the key, and more often than not, it will result in a more accurate forecast.

The consensus not only reduces the margin of error, but it also provides some consistency and reliability. As was mentioned previously, an individual forecaster can beat the consensus, however, it is impossible to know which of hundreds of forecasts will be the most accurate ahead of time. As is evident in our previous example, the forecasts from individual analysts can vary significantly from one to another, whereas the consensus will consistently provide accurate forecasts.

Forecasting isn’t perfect, but does it need to be?

Forecasting is a science, but it isn’t an exact science. They may not be perfect, but forecasts are still very important to businesses and governments, as they shed light on the unforeseen future, helping them to make vital decisions on strategy, plans and budgets.

So, should you trust forecasts? That is a tough question to answer. Yes, forecasting is complicating and, yes, forecasts are notoriously inaccurate and there are few ways to consistently improve forecast accuracy. The point is, however, that forecasts don’t necessarily need to be perfect to be useful. They just need to be as accurate as possible. One such way to do so is leveraging the wisdom of a crowd of analysts to produce a consensus forecast.

As French mathematician, physicist and philosopher Henri Poincaré put it, “It is far better to foresee even without certainty than not to foresee at all.”

The consensus forecast is a more accurate way to “foresee.”

Useful links

OECD forecasting methods and analytical tools

OECD Economic outlook, analysis and forecasts

Academic research on consensus forecasts

“Consider what we have learned about the combination of forecasts over the past twenty years. (…) The results have been virtually unanimous: combining multiple forecasts leads to increased forecast accuracy. This has been the result whether the forecasts are judgmental or statistical, econometric or extrapolation. Furthermore, in many cases one can make dramatic performance improvements by simply averaging the forecasts.”- Clemen Robert T. (1989) “Combining forecasts: A review and annotated bibliography” International Journal of Forecasting 5: 559-560

“A key reason for using forecast combinations […] is that individual forecasts may be differently affected by non-stationaries such as structural breaks caused by institutional change, technological developments or large macroeconomic shocks. […] Since it is typically difficult to detect structural breaks in ‘real terms’, it is plausible that on average, across periods with varying degrees of stability, combinations of forecasts from models with different degrees of adaptability may outperform forecasts from individual models.” Aiolfi M. and Timmermann A. (2004) “Structural Breaks and the Performance of Forecast Combinations”

 

 

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