Why does the federal jobs report get revised?

Revisions to the jobs report issued by the Bureau of Labor Statistics (BLS) are at the center of a political firestorm after President Trump fired the agency’s head earlier this month.

The agency’s most recent report revised down employment numbers for May and June by a whopping 258,000 jobs, drawing accusations by the president and his allies that the numbers were manipulated for political purposes.

That’s not true, most economists say. BLS instead revises its numbers to account for more information from its nationwide surveys, and the agency remains the gold standard for macroeconomic data in the U.S.

Still, there are measures that the bureau could take, its supporters say, to modernize the collection of its survey data, particularly for its population survey — one of two surveys used