Fig. 2.

Slope coefficient bias for smoking status and education categories with memory cognitive function outcome when imputing the outcome together with either smoking status or education. a - % bias, b - mean square error ratio, c – coverage. a - % bias closest to zero indicates least bias approach. b - Ratios relative to available case analysis MSE. Ratio less than one indicates less bias compared to the available case analysis. c - Coverage close to 95% indicate proper control of the type I error rate for testing a null hypothesis of no effect