Nka na ụzụ odide ntụkwasị

Nkebi a ga-a mgbakọ na mwepụ obibia ụfọdụ na ziekwa na ihe gbasara nke puru na-abụghị nke puru omume samples. Ọ ga-abịarukwa on Särndal, Swensson, and Wretman (2003) na Särndal and Lundström (2005) .