Skip to main content

Table 1 A summary of selection bias prior to matching and bias reduction post matching

From: Propensity score interval matching: using bootstrap confidence intervals for accommodating estimation errors of propensity scores

Matching Method

Sample Size

SB for Logit of PS (%)

PBR for Logit of PS (%)

Average of Absolute SB across 74 Covariates (%)

Average of PBR across 74 Covariates (%)

Prior to Matching

nR = 1990 nU = 4327

78.73

16.22

Post Matching

Nearest Neighbor

nR = nU = 1990

30.23

75.21

4.84

53.32

Optimal

nR = nU = 1990

30.23

75.21

4.91

55.15

Mahalanobis Caliper

nR = nU = 1701

61.04

51.79

10.16

25.70

Caliper

nR = nU = 1539

1.96

98.41

1.00

76.78

50 % Interval

nR = nU = 1483

−2.89

97.69

1.43

76.50

68 % Interval

nR = nU = 1538

−0.46

99.64

1.25

79.24

95 % Interval

nR = nU = 1713

9.52

92.55

1.33

79.12