Harrell C-Index

What is the Harrell C-Index? 

The Harrell’s C-index (also known as Concordance Index) is a statistical measure used to assess the discriminatory power of survival models. It evaluates how well the model predicts the order of events, such as patient survival or disease progression, by comparing predicted risk scores with actual outcomes. The C-index ranges from 0 to 1, with higher values indicating better model performance. A C-index of 0.5 suggests no discriminatory ability (similar to random guessing), while a C-index of 1 indicates perfect discrimination. 

Why is Harrell’s C-Index important? 

Harrell’s C-index is a fundamental metric for assessing the performance of survival and time-to-event models, providing insight into how well a model can differentiate between individuals with varying risks. Its simplicity and interpretability make it an essential tool in clinical research, medical decision-making, and predictive modeling across industries.