The government agency charged with calculating the nation's growth rate is acknowledging problems with its numbers and pledging a series of fixes over the next several months.
In a statement to CNBC, the Bureau of Economic Analysis said it's "aware of issues" in it gross domestic product data and "is developing methods to address what it has found."
The BEA statement comes after CNBC, in a detailed report in April, showed that first-quarter GDP data have been weaker than the other three quarters for the past 30 years and substantially weaker in the past five.
Several economists, including researchers at the San Francisco and Philadelphia Federal Reserve banks and many Wall Street economists, have since confirmed CNBC's findings. Many attribute the problem to what is known as "residual seasonality," which are seasonal patterns that remain in the data even though the information is already adjusted for seasonal variations.
Nicole Mayerhauser, chief of BEA's national income and wealth division, which oversees the GDP report, said in the statement that the agency has identified several sources of trouble in the data, including federal defense service spending. Mayerhauser said initial research has shown this category of spending to be generally lower in the first and the fourth quarters. The BEA will also be adjusting "certain inventory investment series" that have not previously been seasonally adjusted. In addition, the agency will provide more intensive seasonal adjustment quarterly service spending data.
Mayerhauser said that an initial round of revisions will be completed by July 30, in time to be incorporated into the annual benchmark revisions of GDP. These revisions, however, will only go back three years, to the years beginning in 2012.
"Longer term— beyond July 30—BEA will continue looking at components of GDP to determine if there are opportunities to improve seasonal adjustment methodologies," she said. "Should BEA identify other areas of potential residual seasonality, BEA will develop methods to address these findings."