Revisiting the Links Between Numeracy and Decision Making: Replication Registered Report of Peters et al. (2006) With an Extension Examining Confidence

Abstract

Numeracy is individuals’ capacity to understand and process basic probability and numerical information required to make decisions. We conducted a Replication Registered Report of Peters et al. (2006) examining numeracy as a predictor of positive-negative framing effect (Study 1), frequency-percentage effect (Study 2), ratio effect (Study 3), and bets effect (Study 4). With an online US American Amazon Mechanical Turk sample (N = 860), our replication using the target’s dichotomizing of the numeracy measure found support for the original findings regarding interactions between numeracy and three decision-making effects. Numeracy was associated with weaker framing effect (η2p = 0.01, 90% CI [0.00, 0.02]), weaker ratio bias (Cramer’s V = 0.17, 95% CI [0.10, 0.24]), and stronger bets effect (η2p = 0.02, 90% CI [0.01, 0.04]), yet we found no support for the frequency-percentage effect (η2p = 0.00, 90% CI [0.00, 0.01]). However, we found support for associations with all four studies when treating numeracy as a continuous variable. We extended the replication to examine confidence, yet the results were mixed with support found for only three conditions (Study 1 positive framing condition: r = -0.11, 95% CI [-0.20, -0.02]; Study 3: r = 0.15, 95% CI [0.08, 0.21]; Study 4 no-loss bet condition: r = 0.10, 95% CI [0.01, 0.20]), suggesting a much weaker and more complex relationship than anticipated. Materials, data, and code are available on: https://osf.io/4hjck/.