Most commentators viewed the February jobs report released on March 7 as good news, indicating that the labor market is on a favorable growth path. A more careful reading shows that employment actually fell—as it has in four out of the past six months and in more than one-third of the months during the past two years.

Although it is often overlooked, a key statistic for understanding the labor market is the length of the average workweek. Small changes in the average workweek imply large changes in total hours worked. The average workweek in the U.S. has fallen to 34.2 hours in February from 34.5 hours in September 2013, according to the Bureau of Labor Statistics. That decline, coupled with mediocre job creation, implies that the total hours of employment have decreased over the period.

Job creation rose from an initial 113,000 in January (later revised to 129,000) to 175,000 in February. The January number frightened many, while the February number was cheered—even though it was below the prior 12-month average of 189,000.

The labor market's strength and economic activity are better measured by the number of total hours worked than by the number of people employed. An employer who replaces 100 40-hour-per-week workers with 120 20-hour-per-week workers is contracting, not expanding operations. The same is true at the national level.

The total hours worked per week is obtained by multiplying the reported average workweek hours by the number of workers employed. The decline in the average workweek for all employees on private nonfarm payrolls by 3/10ths of an hour—offset partially by the increase in the number of people working—means that real labor usage on net, taking into account hours worked, fell by the equivalent of 100,000 jobs since September.