Image credit: Intel. 

Market research firm IDC cut its worldwide personal computer shipment forecast on Thursday, revising its full-year forecast downward to a 7.3% decline, which MarketWatch reports is about 2 percentage points below its previous projections.

Though microprocessor specialist Intel (NASDAQ:INTC) has been working hard to diversify beyond sales of chips for PCs, it still derives the majority of its revenue from that segment. As a result, one would think that this cut to the forecast would be bad news for shareholders in the chip giant.

It isn't. Here's why.

Intel's way ahead of IDC

On Intel's most recent earnings call on April 19, the company reduced its own expectations for the total addressable market for personal computers for the year.

"We now expect the PC market to decline in the high single digits in 2016 versus our prior forecast of mid-single digit decline," Intel CFO Stacy Smith said in a prepared statement.

In other words, IDC waited nearly two months to revise its forecast lower, even though the company that's in the best position to call industry-wide PC trends had already publicly predicted the drop.

Since Intel already warned investors about the steeper decline ahead, both investors and Wall Street analysts have already readjusted their expectations to fit that forecast. This means that from an investment perspective, the report from IDC should not have an impact.

The problem with forecasts

Research firms like IDC compile industry-wide forecasts that both investors and businesses rely on. The problem with these forecasts, though, is that they are often inaccurate, and their accuracy naturally diminishes rapidly the further out into the future they project. This doesn't just apply to forecasts about the PC market, but for other tech markets such as tablets and smartphones.

The forecasts, from what I can tell, also tend to skew optimistic. For example, late last year, IDC predicted that PC sales would decline just 3.1% in 2016.  Given that the current 7.3% decline figure represents a 2 percentage point decline from its previous estimate, this means that since December 2015, IDC has revised its worldwide PC shipment estimates down significantly twice in the span of roughly half a year.

In other words, don't make investment decisions solely based on what third-party market research firms say -- pay attention to what the top companies in the industry are saying.

The 2017 forecast looks too high

According to IDC, the PC market is only expected to decline by 1.7% in 2017, a much better showing than what the firm now expects for 2016. I think that this figure is far too optimistic. If IDC's 7.3% figure turns out to be correct for the year, it would represent a narrowing of the year-over-year decline from the prior year by around 3% (2015 PC sales were down 10.6% according to IDC).

For my own investment purposes, I am going to assume that the decline narrows from the "high single digit" levels that Intel expects this year, but not by more than 3 percentage points. So, for now, I expect PC sales to drop by between 4% and 6%. This is a less rosy picture than the one that IDC is currently painting, but in my view, it is far more realistic.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.