IOA Calculator

Calculate Interobserver Agreement (IOA) to assess data reliability in ABA research and practice. Choose from multiple calculation methods based on your data type.

1

Select IOA Method

2

Enter Data

Compares total counts between observers. Simple but may mask timing differences.

What is IOA?

Interobserver Agreement (IOA) measures the extent to which two or more observers record the same data when observing the same behavior.

High IOA indicates reliable data collection procedures and clear operational definitions. The standard criterion is typically 80% or higher.

When to Calculate IOA

  • -During baseline and intervention phases
  • -At least 20-33% of sessions
  • -After observer training
  • -When publishing research

Reliability Standards

Excellent90%+
Good80-89%
Acceptable70-79%
Questionable60-69%
Poor<60%

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