Widening social inequalities in smoking cessation in Spain, 1987-1997

Abstract
Data were obtained from the Spanish NHISs conducted in 1987, 1993, 1995, and 1997 among the non-institutionalised population by means of personal interviews. Sample sizes of the surveys were 27 756 subjects in 1987; 21 120 in 1993; and 6400 both in 1995 and 1997. Non-response rates ranged from 10% in 1987 to 15% in 1997. In the four surveys, a multistage random sampling strategy with stratification was used.