The economy added 120,000 jobs in March, half of February's gain of 240,000 and the fewest in five months. Yet the unemployment rate fell for the first time since January.

How did the rate fall despite such a small job gain? Because the government does one survey to learn how many jobs were created and another survey to determine the unemployment rate. Those surveys can produce results that sometimes seem to conflict.

One is called the payroll survey. It asks mostly large companies and government agencies how many people they employed during the month. This survey produces the number of jobs gained or lost. In March, the payroll survey showed that companies added 121,000 jobs, and federal, state and local governments cut 1,000.

Editor's Note: Wall Street Insider: The System Is Rigged

The other is the household survey. Government workers ask whether the adults in a household have a job. Those who don't are asked whether they're looking for one. If they are, they're considered unemployed. If they aren't, they're not considered in the work force and aren't counted as unemployed.

The household survey produces each month's unemployment rate.

In March, the household survey showed that the number of people who say they have a job fell by 31,000 and the number of people looking for a job fell by 79,000. That lowered the unemployment rate to 8.2 percent.

Unlike the payroll survey, the household survey captures farm workers, the self-employed and people who work for new companies. It also does a better job capturing hiring by small businesses.

But the household survey is more volatile from month to month. The Labor Department surveys just 60,000 households, a small fraction of the more than 100 million U.S. households.

By contrast, the payroll survey seeks information from 140,000 companies and government agencies — and they employ roughly one-third of non-farm employees. The employers send forms to the Labor Department noting how many people they employ. They also provide wages, hours and other details.

Most Americans focus more on the unemployment rate, which comes from the household survey. But economists generally prefer the jobs figure from the payroll survey.

Economists note that the surveys tend to even out over time. In the past year, the payroll survey reports that employers added 1.9 million jobs, while the household survey found close to 2.3 million more people who said they found work.

Editor's Note: Wall Street Insider: The System Is Rigged