The unexpected increase in the New York state population that emerged in the 2020 U.S. Census is casting a shadow of doubt on the accuracy of the final data, experts warn.

According to a preliminary analysis published this week by the U.S. Census Bureau, New York has more than 818,000 more residents than were predicted by the department’s April 1, 2020, estimate. The official decennial count shows 20,201,249 residents, compared to 19,382,373 predicted by the Census Bureau a year earlier.