Selection Algorithm
No synthetic	44.36 ± 1.51	47.33 ± 0.57	63.40 ± 1.33
Center matching	51.75 ± 2.01	55.67 ± 0.63	66.00 ± 0.58
DS3	52.33 ± 2.07	58.80 ± 0.96	66.68 ± 0.63
K-means	51.14 ± 1.90	56.93 ± 0.46	65.71 ± 0.71
Random	50.45 ± 1.41	55.86 ± 0.73	65.67 ± 0.82
Text matching	51.38 ± 1.51	55.81 ± 0.65	65.76 ± 1.00
Covariance matching Ours	52.65 ± 1.47	58.78 ± 0.53	67.04 ± 0.83
Real upper bound	61.08 ± 2.54	65.38 ± 0.51	74.35 ± 0.56