Table 1.

Data Used by GEE and ML for Parameter Estimates by Missingness Pattern

Variable(s) Missing	${\widehat{\beta }}_1^{(1)}$	${\widehat{\beta }}_1^{(2)}$
X1 only	*†	‡ available cases of Y and X2
X2 only	‡ available cases of Y and X1	§†
Both Y and X1	*†	‡ complete cases of Y and X2
Both Y and X2	‡ complete cases of Y and X1	§†
Y only	*†	§†
Both X1 and X2	*†	§†

^*GEE is based on complete cases of Y and X₁

^§GEE is based on complete cases of Y and X₂

^†ML is a combination of expressions involving all observed data

^‡ML estimate is the same as the GEE estimate