Estimation under not Missing at Random Nonresponse // Methods to estimate finite-population parameters under nonresponse that is not missing at random (NMAR, nonignorable). Incorporates auxiliary information and user-specified response models, and supports independent samples and complex survey designs via objects from the 'survey' package. Provides diagnostics and optional variance estimates. For methodological background see Qin, Leung and Shao (2002) doi:10.1198/016214502753479338 and Riddles, Kim and Im (2016) doi:10.1093/jssam/smv047.