Census Campaign executive director Victoria Kovari looks over a Detroit map showing city neighborhoods that were undercounted in the 2010 census.AP Photo/Corey WilliamsEditor’s note: Researchers have long known that certain groups are vulnerable to being undercountedin the decennial census. But the 2020 census has raised a new set of concernsaround hard-to-count populations and general confusion with the process. The coronavirus pandemic only adds more uncertainty. Demographer Rebecca Tippettexplains the factors at play.A long historyHistorically, communities that have been more likely to be u…