Each month, the U.S. Census Bureau and the Bureau of Labor Statistics conduct the Current Population Survey which is used to calculate key economic indicators such as the unemployment rate as well as the wage rate.

While the survey data is meant to be representative of the entire workforce, there is growing concern that the questions fail to capture non-traditional work or non-primary work. As MarketWatch previously reported, many workers may not think of themselves as having a primary job and, therefore, do not often report side hustles and other freelance work.

“ ‘Our study tells us there is an issue with how people are responding to the CPS employment questions.’ ” — Katherine Abraham, who served as commissioner of the BLS from 1993 to 2001

However, by asking more specific questions, it may be possible to better understand the work that would not otherwise appear in the monthly unemployment report, according to a study released Monday. The researchers not only asked about the type of additional or non-primary work respondents are involved in, but also asked about the number of hours worked and salary earned.

The researchers found that nearly 4% of those currently labelled as not having any job, and nearly 22% altogether, had their employment misclassified.

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The study was written by Katherine Abraham, a professor of economics and survey methodology at the University of Maryland who also served as commissioner of the BLS from 1993 to 2001, and Ashley Amaya, a research survey methodologist at RTI, a nonprofit research institute based in Piedmont, N.C.

“ Currently, the BLS does not track the gig economy partially because there is no agreed upon definition of gig work. ”

“Our study tells us there is an issue with how people are responding to the CPS employment questions, but it does not allow us to quantify the magnitude of the problem,” said Abraham. The survey sample was not representative of the population, she added.

Still, Abraham said additional probing into working arrangements may help uncover more meaningful insights about the workforce that would not appear in the Current Population Survey otherwise.

Some of the questions the researchers ask focus on a sector known as the “gig economy”. Currently, the BLS does not track the gig economy partially because there is no agreed upon definition of gig work. “In the CPS, we are looking for information about people’s main jobs only and not secondary jobs or additional jobs,” Karen Kosanovich, an economist at the BLS, told MarketWatch.