(Bloomberg) The way some parts of U.S. gross domestic product are calculated are about to change in the wake of the debate over persistently depressed first-quarter growth.

In a blog post published Friday, the Bureau of Economic Analysis listed a series of alterations it will make in seasonally adjusting data used to calculate economic growth. The changes will be implemented with the release of the initial second-quarter GDP estimate on July 30, the BEA said.

Although the agency adjusts its figures for seasonal variations, growth in any given first quarter still tends to be weaker than in the remaining three, economists have found, a sign there may be some bias in the data. It’s a phenomenon economists call “residual seasonality.”

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