Efficacy = endowment x efficiency: Revisiting efficacy and endowment effects in a public goods dilemma

Chi-ching YU, Wing-tung AU, Ka Shing Kevin CHAN

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This article reexamines the efficacy and endowment effects in public good (PG) dilemma by conceptualizing that efficacy = endowment × efficiency. Endowment is the resource that a person can contribute. Efficiency is the impact of a unit of endowment. Efficacy is the total impact of contribution. The authors used a group project scenario to simulate a continuous contribution PG dilemma. The 2 × 2 × 2 × 2 experimental design manipulated own efficiency and own endowment as within-subject variables and the other persons' efficiency and endowment as between-subject variables. Results indicate that cooperation was mainly affected by one's endowment and others' efficiency. The authors distinguished among 3 types of efficiency effects: (a) an own-absolute-efficiency effect that efficient people put in more effort regardless of others' efficiency, (b) an other-absolute-inefficiency effect that people put in more effort when others are inefficient, and (c) a relative-inefficiency effect that inefficient people put in less effort in the presence of efficient people. Contrasting previous robust findings on efficiency, they identified a situation in which efficiency has no effects-when one has more endowment than do others. Copyright © 2009 American Psychological Association.
Original languageEnglish
Pages (from-to)155-169
JournalJournal of Personality and Social Psychology
Issue number1
Publication statusPublished - Jan 2009



Yu, C.-C., Au, W.-T., & Chan, K.-S. K. (2009). Efficacy = endowment x efficiency: Revisiting efficacy and endowment effects in a public goods dilemma. Journal of Personality and Social Psychology, 96(1), 155-169. doi: 10.1037/a0012879


  • Efficacy
  • Efficiency
  • Endowment
  • Public goods