Despite high objective numeracy, lower numeric confidence relates to worse financial and medical outcomes

Greater objective ability is thought to lead to more confidence and success across domains. We investigated instead whether objective numeracy and numeric confidence might "mismatch" sometimes and, critically, interact in predicting financial and medical outcomes. The results of 2 studies (secondary analyses of a diverse internet panel and primary analysis of patients with systemic lupus erythematosus) revealed that being more objectively numerate benefits those who are more numerically confident, but not the less numerically confident. Enjoying good outcomes in finances and health appears to require the persistence of numeric confidence and also the human capital of objective numeracy. The patterns further suggest that improving 1 numerical competency without considering the other could cause harm.