Calculate percent agreement between two raters from agreements and total items or a 2×2 table, or find the relative percent difference between two values.

Count one agreement when the two ratings for an item match.

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Percent Agreement and Percent Difference Formulas

The following example problem outlines the steps and information needed to calculate the relative percent difference (percent difference) between two values, and the formula below also includes rater percent agreement.

PA & = (Agreements) / (Total Observations) × 100 \ RPD & = (|V1 - V2|) / (((V1 + V2) / (2))) × 100

Variables:

  • PA is the Percent Agreement (%)
  • Agreements is the number of matching ratings/decisions
  • Total Observations is the total number of items rated/observed (agreements + disagreements)
  • RPD is the Relative Percent Difference (percent difference) (%)
  • V1 is the first value 
  • V2 is the second value 

How to Calculate Percent Agreement?

The following steps outline how to calculate percent agreement (rater agreement) or relative percent difference (value comparison), depending on which calculation mode you use.

  1. First, choose the calculation mode you need: Percent agreement from counts or a 2×2 table, agreements needed for a target, or Relative percent difference (value comparison). 
  2. For Value Comparison, determine the first value (V1) and the second value (V2). 
  3. Use the correct formula: RPD = |V1−V2| / ((V1+V2)/2) * 100, or PA = (Agreements / Total Observations) * 100.
  4. Finally, calculate the result.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge (Value Comparison / RPD).

first value = 30

second value = 40

RPD = |V1-V2| / ((V1+V2)/2) *100 = |30-40| / ((30+40)/2) * 100 = 28.57%