The Impact of an RDD to ABS/Mail Sample Design and Mode Change in the 2021 New York City Community Health Survey (CHS) Michael Witt, Abt Associates; Steven Fernandez, New York City Department of Health and Mental Hygiene; Stephen Immerwahr , New York City Department of Health and Mental Hygiene; Stas Kolenikov, NORC; Amber Levanon Seligson, New York City Department of Health and Mental Hygiene; Martha McRoy, Abt Associates; John Sokolowski, Abt Associates; Nicholas Ruther, Abt Associates; Stephanie Zimmer, Abt Associates