An explanation of the findings from the federally financed survey to assess long-term care needs and finances of those 65 and older.The Times/KFF Health News data analysis was based on the Health and Retirement Study, a nationally representative longitudinal survey of about 20,000 people over age 50. The analysis defined people ages 65 and above as likely to need long-term care if they were assessed to have dementia, or if they reported having difficulty with two or more out of six activities of daily living. The six activities are bathing, dressing, eating, getting in and out of bed, walking across a room and using the toilet. The Langa-Weir classification of cognitive function, a related data set, was used to identify respondents with dementia. The analysis’ definition of needing long-term care assistance is conservative and is in line with criteria most long-term care insurers use in determining whether they will pay for services.People were described as recipients of long-term care help if they reported receiving assistance in the month before the survey interview or if they lived in a nursing home. The analysis was developed in consultation with Norma Coe, an associate professor of medical ethics and health policy at the Perelman School of Medicine at the University of Pennsylvania.The financial toll on middle-class and upper-income people needing long-term care was examined by reviewing data that the H.R.S. collected between 2000 and 2021 on wealthy Americans, those whose net worth at age 65 was in the 50th to 95th percentile, totaling anywhere from $171,365 to $1,827,765 in inflation-adjusted 2020 dollars. This group excludes the super-wealthy. Each individual’s wealth at age 65 was compared with their wealth just before they died to calculate the percentage of affluent people who exhausted their financial resources and the likelihood that would occur among different groups.To calculate how many people were likely to need long-term care, how many people needing long-term care services were receiving them, and who was providing care to people receiving help, we looked at people ages 65 and older of all wealth levels in the 2020-21 survey, the most recent.The U.S. Health and Retirement Study is conducted by the University of Michigan, and funded by the National Institute on Aging and the Social Security Administration.The analysis was conducted by Albert Sun, a graphics editor for The Times, and Holly K. Hacker, a data editor for KFF Health News, part of the organization formerly known as the Kaiser Family Foundation.