Caution in Questionnaire Methods and Reverse Causation

Questionnaire methods in studies may be biased as individuals tend to report what they want to believe about themselves. This bias can lead to misleading correlations, such as the lack of association between ice cream consumption and diabetes. Reverse causation is another factor where the observed relationship may be misleading. An example is the correlation between mouthwash and oral cancer where it was the oral cancer causing bad breath that led to increased mouthwash use, not the other way around. Similarly, in the case of ice cream consumption and health, individuals who consume less ice cream may already be less healthy to begin with due to existing health issues or conscious effort to avoid unhealthy foods, resulting in a reverse causation scenario.