Table 2.

Variables involved in missing data mechanisms and the consequent expected bias (compared to the true population values) of coefficient estimates from using the complete records to fit a linear regression and logistic regression of Y on X₁, X₂

Mechanism depends on	Biased estimation of parameters using complete records
	Typical regression				Logistic regression
	Constant	Coefficient of X1	Coefficient of X2		Constant	Coefficient of X1	Coefficient of X2
Y	Yes	Yes	Yes		Yes	No	No
X 1	No	No	No		No	No	No
X 2	No	No	No		No	No	No
X1, X2	No	No	No		No	No	No
Y, X1	Yes	Yes	Yes		Yes	Yes	No
Y, X2	Yes	Yes	Yes		Yes	No	Yes
Y, X1, X2	Yes	Yes	Yes		Yes	Yes	Yes