The NSOC sample was drawn from 4935 eligible informal caregivers to 2423 eligible NHATS respondents. (For a small number of NHATS respondents identifying more than five eligible caregivers, five caregivers were selected randomly.) Eligible NHATS respondents refused to provide contact information for 1573 eligible caregivers, and of the remaining 3362 caregivers with contact information, 1355 could not be located or refused to respond. The first stage (NHATS) response rate was 68%, and the second stage (caregiver) response rate was 60% (Kasper, Freedman & Spillman 2013). For a “primary caregiver” defined by the number of hours of care provided, the corresponding rates were 73% and 67%. The final NSOC sample consists of 2007 responding caregivers to 1369 NHATS respondents. Sample weights developed for the NSOC take into account differential probabilities of selection and non-response at both the NHATS sample person and caregiver level (Kasper et al. 2013a). We excluded 11 caregivers who had helped within the year prior to interview, but not within the last month, for a final analysis sample of 1996 caregivers.