The line between accurate tools and faulty ones is clear in engineering because engineers calibrate their tools. Engineers do that because they rely most often on exact measurements, not estimates or extrapolations. Unfortunately, that's not always the case outside of engineering.

For instance, many people, including engineers, put a lot of stock in jobless data regularly reported by the U.S. Department of Labor's Bureau of Labor Statistics.

The data influences the U.S. stock and bond markets, the direction of the U.S. economy and even whether the Federal Reserve Board will raise or lower interest rates.

EE Times readers also depend on accuracy in the Bureau of Labor Statistics numbers, and over the last two years many have claimed that the government is vastly undercounting the number of jobless EEs.

They maintain that the number of out-of-work EEs in the United States is much higher than the 26,000 the bureau reported as unemployed for the fourth quarter of 2002.

It's important that engineers as consumers of information realize the government data for what it is: the best and only measure that Washington has for jobless estimates. It is by no means an exact head count of the number of unemployed.

Unemployment data from the Bureau of Labor Statistics is based on a monthly survey of 60,000 households (or about 100,000 people), known as the Current Population Survey. When the data is inflated to represent the entire population, each person in the survey represents 3,000 people.

The Labor Department notes on its Web site: "Chances are 90 out of 100 that the monthly estimate of unemployment is within about 230,000 of the figure attainable from a total census. Since monthly unemployment totals have ranged between about 5 million and 8 million in recent years, possible errors resulting from the sampling are not large enough to distort the total unemployment picture."

But quarterly counts of the joblessness in specific occupations or job titles are less reliable than overall numbers, because they are based on extrapolations of small samples from the survey. In other words, out of 100,000 people interviewed in a month, perhaps 25 or fewer are electronic engineers. They would be extrapolated out as representative of all EEs in the population.

The exact truth about joblessness lies somewhere out there and, until someone comes up with the right tools for an exact head count, we won't know it.

Robert Rivers of the American Engineering Association has tracked engineering unemployment for decades, and puts the number of jobless engineers at three times what the Bureau of Labor Statistics reports.

That may be so, but there's no way to tell for sure.