Consistency of faculty differences in daily smoking between survey I (1992) and survey II (2003), separately for men and women, and between men and women, separately for surveys I and II. Upper row: Regression of smoking in survey II on smoking in survey I. Lower row: Regression of women's on men's smoking. Points indicate prevalence differences (in percentage points) vis-à-vis the medical faculty, adjusted for age and occupation. Solid lines are weighted linear regressions of the differences and dashed lines their 95% confidence bands. b is the regression slope (95% confidence interval).