Table 2. Linkage Ratio Inference Results (in RMSE) on MS^5,a.

	NIST → NIST	UGA-S → UGA-S	NIST → UGA-S	UGA-S → NIST
A30	0.007	0.027	0.104	0.084
A35	0.019	0.020	0.090	0.101
A40	0.066	0.015	0.094	0.050
A45	0.024	0.009	0.080	0.037
A50	0.166	0.013	0.087	0.184
B30	0.044	0.036	0.106	0.101
B35	0.084	0.025	0.086	0.118
B40	0.036	0.018	0.081	0.015
B45	0.080	0.014	0.082	0.001
B50	0.053	0.011	0.081	0.051
C30	0.049	0.040	0.109	0.090
C35	0.115	0.017	0.088	0.109
C40	0.003	0.010	0.086	0.008
C45	0.044	0.010	0.089	0.069
C50	0.036	0.010	0.084	0.030

^aThe row headers indicate the data collection configurations (see the Multilevel Mass Spectrometry section). The column headers indicate the training set (left) and the test set (right). NIST and UGA-S stand for the NIST and UGA-S data sets, respectively. When the training and test sets have the same name, the result is the average RMSE of the 5-fold cross-validation runs.