Selection Algorithm
No synthetic	44.36 ± 1.51	47.33 ± 0.57	63.40 ± 1.33
Center matching	50.06 ± 1.45	54.50 ± 0.62	66.23 ± 0.72
DS3	52.93 ± 1.65	58.69 ± 0.81	68.04 ± 0.71
K-means	51.66 ± 2.10	55.97 ± 0.58	67.00 ± 0.84
Random	49.97 ± 2.45	54.79 ± 0.68	66.57 ± 0.92
Text matching	51.52 ± 1.67	55.17 ± 0.57	67.13 ± 0.45
Covariance matching Ours	54.97 ± 2.60	59.41 ± 0.81	68.87 ± 0.41
Real upper bound	61.08 ± 2.54	65.38 ± 0.51	74.35 ± 0.56