Table 3. Comparison of three medical ontologies in terms of Breadth, Depth and (Depth) Loss, Relative Depth and Relative Depth Loss.

Metric	ICD9 CM (I)	CCPSS (C)	SNOMED (S)	MESH (M)
Breadth1	1.416×10−2	2.259×10−2	3.227×10−2	2.655×10−2
Depth1	2.347×10−6	6.454×10−6	1.049×10−6	1.019×10−5
Relative Depth1	0.365	0.605	0.818	0.687
Depth1 Loss	4.083×10−6	4.218×10−6	0.234×10−6	4.646×10−6
Relative Depth1 Loss	0.635	0.395	0.182	0.313
Breadth2	1.648×10−3	1.405×10−2	9.829×10−3	7.843×10−3
Depth2	0.279×10−6	1.160×10−6	0.158×10−6	2.077×10−6
Relative Depth2	0.055	0.455	0.319	0.272
Depth2 Loss	4.831×10−6	1.387×10−6	3.383×10−7	5.551×10−6
Relative Depth2 Loss	0.945	0.545	0.681	0.728