TABLE 3. Correlation coefficient analysis between 2 factors.

Characteristics		Hematoma expansion	Salvage DC	Postop MLS change
Sphericity index
	Correlation coefficient	−0.265	−0.134	−0.340
	p-value	0.048*	0.323	0.010*
	Number	56	56	56
Hematoma expansion
	Correlation coefficient		0.296	0.335
	p-value		0.027*	0.012*
	Number		56	56
Salvage DC
	Correlation coefficient			0.754
	p-value			<0.001**
	Number			56

We employed the following types of correlation analyses based on the types of variables. (1) Point biserial correlation: sphericity index and hematoma expansion, sphericity index and salvage DC, postop MLS change and hematoma expansion, postop MLS change and salvage DC. (2) Pearson correlation: postop MLS change and sphericity index. (3) Phi coefficient: hematoma expansion and salvage DC. Duplicated or identical variable correlations are highlighted in gray.

DC: decompressive craniectomy, MLS: midline shift.