In a rare and startling addendum to the report, known as the American Community Survey (ACS), the Census Bureau said that the data contained in last year’s release, which depicted poverty, income, and other aspects of life in Philadelphia in 2017, were incorrect. Census officials advised that the erroneous statistics for that year not be used in making comparisons. That admission roiled some city leaders, at the same time confirming their suspicions that those figures had been wrong all along.