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
 Share with license KB…0.4160.4330.4380.4270.409
 Share with license KBK-N0.1130.1220.1160.1190.809
 Share with license KBP-S0.0060.0090.0110.0070.124
Claims data
 Any previous claim0.1520.1700.1800.1820.018
 Any previous injury claim0.0780.0770.0820.0850.687
 Any previous fatality claim0.0150.0160.0160.0160.990
 Number previous claims per accident2.5631.9381.7291.8240.000
 Annualized accident rate0.0790.0970.1040.1030.001
 Phase 1 attrition rate0.1750.2290.2750.2760.000
  • 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.