Youden Index Calculator

Youden Index Calculator calculator can be used to determine the optimal cut-off point for a diagnostic test based on sensitivity and specificity values.

Input Parameters

Calculation Results

Youden Index

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Optimal Cut-off Point

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Calculation Formula

Youden Index = Sensitivity + Specificity - 1

Where:
- Sensitivity = True Positive Rate (TPR)
- Specificity = True Negative Rate (TNR)

Youden Index Calculator Calculator Usage Guide

Learn how to use the Youden Index Calculator to determine optimal diagnostic test cut-off points

How to Use This Calculator

  1. Enter the sensitivity of your diagnostic test as a percentage (e.g., 85.5)
  2. Enter the specificity of your diagnostic test as a percentage (e.g., 92.0)
  3. Click the "Calculate" button to determine the Youden Index and optimal cut-off point
  4. The Youden Index represents the maximum sum of sensitivity and specificity minus one, indicating the best balance between these two parameters
  5. The optimal cut-off point is the probability threshold that maximizes the Youden Index

Understanding the Results

The Youden Index ranges from 0 to 1, where:

  • A value of 0 indicates poor diagnostic performance
  • A value of 1 indicates perfect diagnostic performance
  • The optimal cut-off point is the threshold probability that maximizes the Youden Index

Principle of Youden Index

The Youden Index (J statistic) is calculated as:

Youden Index = Sensitivity + Specificity - 1

This index combines sensitivity and specificity into a single measure that ranges from 0 to 1, with higher values indicating better test performance. The optimal cut-off point is determined by normalizing the sensitivity value relative to the sum of sensitivity and specificity.

Applications

The Youden Index is commonly used in:

  • Determining optimal cut-off points for diagnostic tests
  • Comparing the performance of different diagnostic tests
  • Identifying the best threshold for a continuous test result to classify cases