Table S1.

Balance test: Individual vs. collective action

IndicatorControlPlaceboIndividual actionCollective actionJoint orthogonality (P value)
Vehicle attributes
 Share with license KA…*0.5830.5670.5610.5720.378
(0.011)(0.012)(0.008)(0.008)
[0.300][0.089][0.403]
 Share with license KB…0.4160.4330.4380.4270.409
(0.011)(0.012)(0.008)(0.008)
[0.303][0.100][0.415]
 Share with license KBK-N0.1130.1220.1160.1190.809
(0.007)(0.008)(0.005)(0.005)
[0.392][0.744][0.469]
 Share with license KBP-S0.0060.0090.0110.0070.124
(0.002)(0.002)(0.002)(0.001)
[0.399][0.048][0.614]
Claims data
 Any previous claim0.1520.1700.1800.1820.018
(0.008)(0.009)(0.006)(0.006)
[0.128][0.005][0.003]
 Any previous injury claim0.0780.0770.0820.0850.687
(0.006)(0.006)(0.004)(0.004)
[0.905][0.593][0.348]
 Any previous fatality claim0.0150.0160.0160.0160.990
(0.003)(0.003)(0.002)(0.002)
[0.767][0.891][0.785]
 Number previous claims per accident2.5631.9381.7291.8240.000
(0.211)(0.141)(0.080)(0.096)
[0.015][0.000][0.000]
 Annualized accident rate0.0790.0970.1040.1030.001
(0.005)(0.006)(0.004)(0.004)
[0.013][0.000][0.000]
Attrition
 Phase 1 attrition rate0.1750.2290.2750.2760.000
(0.008)(0.010)(0.007)(0.007)
[0.000][0.000][0.000]
N2,0931,7593,9373,948
  • Table covers only phase 1 vehicles, including both those that were found in phase 2 and those that were not. SEs in parentheses. P values comparing noncontrol groups with control group in brackets.

  • * Vehicle license plates are of the form KXX NNNX, where X represents a letter and N a number. KA… license plates were issued before KB… plates, and among KB… plates, KBK-N were issued before KBP-S.

  • Previous claims refer to claims recorded before recruitment.