 Attrition bias is a type of bias in research. Attrition bias is due to participants dropping out of a study before it's completed leading to a bias sample and results. For example, a longitudinal study on aging where healthier participants are more likely to continue participating can lead to attrition bias. Attrition bias can be dealt with by analyzing and reporting findings accounting for attrition. Consider reasons for dropouts and their potential impact in results.