EXCERPTS:
"The ranks of unemployed individuals grew by 134,000 last month from February, to 15 million, the Department of Labor's Bureau of Labor Statistics says. But it also is plausible, the agency says, that the number of unemployed rose by 500,000. Or, it could have fallen by 200,000.
In fact, at a time when high unemployment tops many people's worries about the economic recovery, the BLS can say only that it is 90% confident that the true change in the number of unemployed in March was somewhere between a drop of 243,000 and an increase of 511,000. In other words, it isn't even clear whether the number of unemployed rose or fell last month. The ranges are similarly broad for seven of the last 10 months—and for more than 75% of the time in the past decade.
This isn't a failing of government or of statisticians, say economists. Instead, it is the inevitable result of trying to measure small changes in a sprawling, complex economy. There is no doubt that the unemployment rate remains near the highest it has been in decades. But the government doesn't really know how much that rate has been changing from month to month, which can be vexing for economists attempting to identify signs of a nascent recovery.
The difficulty, says Patrick O'Keefe, director of economic research for accounting firm J.H. Cohn in Roseland, N.J., "is in providing the public a real-time sense of what is going on." He adds: "Most of the month-to-month changes are not only nonsignificant in a statistical way, but they are very often straddling zero, so you can't even infer the direction of the change has been accurately represented."
