Dataset of the sample.

Many people believe in and use complementary and alternative medicine (CAM) to address health issues or prevent diseases. Empirical evidence for those treatments is either lacking or controversial due to methodological weaknesses. Thus, practitioners and patients primarily rely on subjective references rather than credible empirical evidence from systematic research. This study investigated whether cognitive and personality factors explain differences in belief in CAM and homeopathy. We investigated the robustness of 21 predictors when examined together to obtain insights into key determinants of such beliefs in a sample of 599 participants (60% female, 18-81 years). A combination of predictors explained 20% of the variance in CAM belief (predictors: ontological confusions, spiritual epistemology, agreeableness, death anxiety, gender) and approximately 21% of the variance in belief in homeopathy (predictors: ontological confusions, illusory pattern perception, need for cognitive closure, need for cognition, honesty-humility, death anxiety, gender, age). Individuals believing in CAM and homeopathy have cognitive biases and certain individual differences which make them perceive the world differently. Findings are discussed in the context of previous literature and in relation to other unfounded beliefs.