Generalized robust regression techniques and adaptive cluster sampling for efficient estimation of population mean in case of rare and clustered populations.

Situations when field researchers are tempted to deviate from preselected sampling plan and to include nearby or related units in sample, then adaptive cluster sampling (ACS) offers a nearly completion solution. For rare and clustered populations, Thompson introduced ACS as an effective sampling method when data is not contaminated with outliers. However, traditional approaches produce distorted results when data includes outliers.