The post-hoc fallacy (also termed the post-hoc-ergo-propter-hoc fallacy) has been recognized for centuries with endless relevance. The general concept in medical care is that patients who improve after a treatment are not necessary patients who improve because of a treatment. Modern medicine provides multiple opportunities to examine such pitfalls of judgment due to the prevailing uncertainty, incompleteness of our understanding pathogenic mechanisms, and natural tendency to connect treatments to outcomes. In this study, we will investigate whether judgments about vitamin supplementation might demonstrate the post-hoc fallacy.

We plan to conduct a brief survey of pharmacies portraying a patient in two slightly different versions. One version will portray the patient who feels better after starting a vitamin supplement whereas another version will portray the patient who feels unchanged after starting a vitamin supplement. The patients will be randomly assigned to participants and otherwise contain identical information. Judgments will be measured by eliciting participants recommendation about continuing the vitamin (Appendix_Script).

Inclusion Criteria:

• Community pharmacist

Exclusion Criteria:

• Outside Ontario