The Percent Fragility Index

Abstract

This article proposes the Percent Fragility Index (PFI) as an improved measure of statistical fragility in biomedical research. The PFI quantifies the percentage change in outcomes needed to change a study's statistical significance from positive to negative or vice-versa. The PFI improves upon existing indices by providing an intuitive statistic that is easy to grasp and by accommodating both dichotomous and continuous variables. This approach minimizes dependency. on sample size, a limitation of the commonly used Fragility Index (FI) and Fragility Quotient (FQ). The FI measures the minimum number of outcome events required to reverse statistical significance, and the FQ divides the FI by the total sample size. The PFI enhances the interpretability and validity of fragility assessments. PFI facilitates a more critical understanding of research outcomes by offering readers a more precise estimate of study fragility.