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Field
Power calculation: Minimum Detectable Effect Size for Main Outcomes
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Before
Ambiguity Aversion Index (b-index)
Power analysis for the b-index was conducted via Monte Carlo simulation (1,000 repetitions, α = 0.05, two-sided) in Stata. The primary test (H01) is a difference-in-differences comparing the within-subject change from Ellsberg-Gains to Predation-Gains across Rabari and Non-Rabari. The target effect size is 0.14 (28.6% of SD) b-index points, anchored to the difference between Natural and Artificial Gains conditions in Watanabe et al. (2024). Using a standard deviation of 0.490 (the maximum SD across gain-domain treatments in Watanabe et al., 2024) and a within-subject correlation of 0.50 (based on the intra cluster correlation (ICC) reported in Anantanasuwong et al., 2024), a sample of 210 subjects per group achieves a simulated power of 81.2%.
Ambiguity Insensitivity Index (a-index)
For the a-index, the primary test (H02) follows the same difference-in-differences structure. The target effect size is 0.20 (41.7% of SD) a-index points, again anchored to Watanabe et al. (2024). Using a standard deviation of 0.480 and a within-subject correlation of 0.30 (Anantanasuwong et al., 2024), a sample of 210 subjects per group achieves a simulated power of 96.2%. In both cases the standard deviations are chosen conservatively as the maximum observed within their respective domains in Watanabe et al. (2024), so the reported power figures are lower bounds on true power.
References:
Watanabe, M., & Fujimi, T. (2024). Ambiguity attitudes toward natural and artificial sources in gain and loss domains. Journal of Risk and Uncertainty, 68(1), 51-75.
Anantanasuwong, K., Kouwenberg, R., Mitchell, O. S., & Peijnenburg, K. (2024). Ambiguity attitudes for real-world sources: Field evidence from a large sample of investors. Experimental Economics, 27(3), 548-581.
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After
Ambiguity Aversion Index (b-index)
Power analysis for the b-index was conducted via Monte Carlo simulation (1,000 repetitions, α = 0.05, two-sided) in Stata. The primary test (H01) is a difference-in-differences comparing the within-subject change from Ellsberg-Gains to Predation-Gains across Rabari and Non-Rabari. The target effect size is 0.14 (28.6% of SD) b-index points, anchored to the difference between Natural and Artificial Gains conditions in Watanabe et al. (2024). Using a standard deviation of 0.490 (the maximum SD across gain-domain treatments in Watanabe et al., 2024) and a within-subject correlation of 0.50 (based on the intra cluster correlation (ICC) reported in Anantanasuwong et al., 2024), a sample of 210 subjects per group achieves a simulated power of 81.2%.
Ambiguity Insensitivity Index (a-index)
For the a-index, the primary test (H02) follows the same difference-in-differences structure. The target effect size is 0.20 (41.7% of SD) a-index points, again anchored to Watanabe et al. (2024). Using a standard deviation of 0.480 and a within-subject correlation of 0.30 (Anantanasuwong et al., 2024), a sample of 210 subjects per group achieves a simulated power of 96.2%. In both cases the standard deviations are chosen conservatively as the maximum observed within their respective domains in Watanabe et al. (2024), so the reported power figures are lower bounds on true power.
The design also achieves at least 80% power for each secondary hypothesis.
References:
Watanabe, M., & Fujimi, T. (2024). Ambiguity attitudes toward natural and artificial sources in gain and loss domains. Journal of Risk and Uncertainty, 68(1), 51-75.
Anantanasuwong, K., Kouwenberg, R., Mitchell, O. S., & Peijnenburg, K. (2024). Ambiguity attitudes for real-world sources: Field evidence from a large sample of investors. Experimental Economics, 27(3), 548-581.
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