CHAPEL HILL, N.C. (MarketWatch) — Lakshman Achuthan’s recession prediction from 14 months ago has arguably been the most celebrated economic forecast of modern times.

Unfortunately for him — though fortunately for the rest of us — a recession has yet to come to pass. And therein lies a story.

To be sure, it may still be premature to declare his prediction to have been flat-out wrong. But at some point, perhaps very soon, a recession taking place will be insufficient to resurrect his prediction. After all, it’s only trivially true that a recession will occur someday.

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Achuthan, of course, is co-founder of, and chief operations officer at, the Economic Cycle Research Institute, or ECRI. Prior to the last 16 months, ECRI had one of the most revered economic-forecasting track records. Fairly or unfairly, many waxed rhapsodic about how it, and he, had never been wrong.

So Achuthan sent shockwaves through Wall Street when, in September 2011, he declared that another recession was “inescapable.”

He repeated that forecast on numerous occasions in subsequent months — and, beginning this past July, he furthermore began to flatly assert that the U.S. was in a recession already. (For a chronology of Achuthan’s recession pronouncements, I refer you to the careful documentation prepared by Doug Short, vice president of research at Advisor Perspectives.)

The table below shows how real (inflation-adjusted) gross domestic product has grown since Achuthan made his forecast.

% growth in real GDP 2011: Fourth quarter 4.1% 2012: First quarter 2.0% 2012: Second quarter 1.3% 2012: Third quarter 2.0%

Furthermore, the current best guess is that, later this week, third quarter GDP growth will be revised upwards to 2.9% from the initially reported 2.0%.

I think you will agree that these growth rates are in no way consistent with Achuthan’s confident predictions of an imminent recession. Indeed, the quarter in which he said, at its beginning, that a recession was already underway experienced stronger growth than in the previous one.

What can we say about his prediction, even though the jury may still be out on it?

It reminds me of any of a number of similarly bold forecasts made over the years by the investment advisory editors I monitor. In reviewing how they reacted when their predictions did not immediately come to pass, I think we can imagine the pressures under which Achuthan has been — and, in the process, draw several important investment lessons about how we should approach any investment predictions:

Humility is a virtue. Nothing is certain, as the saying goes, other than death and taxes. It’s far more responsible to couch things in terms of probabilities rather than certainties. Saying that something is “inescapable” is a good way of getting attention, but not particularly intellectually honest.

Objectivity is not easily maintained, especially when career risk is taken into account. Once a forecast is made public, and reputations are on the line, the forecaster starts viewing the data through colored glasses — pouncing on any data that vindicate that forecast and downplaying data that do not. Though Achuthan is far too sophisticated to engage in the more shameless ways in which many advisory service editors have in the past sacrificed objectivity, I wonder whether even he succumbed earlier this year when he began to argue that the GDP data are painting an inaccurate picture. After all, a recession is widely defined as two successive quarters of GDP decline — and if he wanted to have his prediction judged by some alternate criteria, he should have specified that in advance.

Success leads to overconfidence. There’s nothing like a string of successful forecasts, as Achuthan had, to encourage any one of us to go dangerously out on a limb with our next forecast. Just take the classic case of the overconfidence genre from the investment-advisory-service arena: Joe Granville, editor of the Granville Market Letter. After successfully predicting a stock market top in early 1981, and having his picture appear on the front page of the New York Times for all the mini-crashes his bearish utterances were creating around the world, Joe became overly impressed with his predictive prowess. He started trying to predict when earthquakes would occur, and argued that he deserved the Nobel Prize in economics for unlocking the key to the stock market. Then came the great bull market in 1982, which Granville utterly failed to foresee — and continued to deny for years thereafter.

Inertia is a powerful force. Ironically, this is true regardless of whether you have been right or wrong. As Jeremy Grantham of GMO brilliantly put it at the bottom of the bear market in March 2009: “Those who were over-invested [during the bear market] will be catatonic and just sit and pray. Those few who look brilliant, oozing cash, will not want to easily give up their brilliance. So almost everyone is watching and waiting with their inertia beginning to set like concrete.”

The bottom line? A recession could still occur, at any time. The last thing I intend, in discussing Achuthan’s prediction, is for any of us to conclude smugly that the economy is immune to decline.

But I am nevertheless reminded of the late great Harry Browne, the one-time investment-advisory-service editor who became the Libertarian Party’s candidate for president in the 1990s, and who pleaded with readers not to bet all or nothing on any one prediction or adviser — no matter how good his or her record.

In his classic book from the 1980s entitled “How The Best-Laid Investment Plans Usually Go Wrong,” Browne wrote: “Almost nothing turns out as expected. Forecasts rarely come true, trading systems never produce the results advertised for them, investment advisers with records of phenomenal success fail to deliver when your money is on the line, the best investment analysis is contradicted by reality. In short, the best-laid investment plans usually go wrong. Not sometimes, not occasionally — but usually.”

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