Interobserver agreement (IOA) serves what primary purpose?

• A. It ensures data reliability and accuracy by showing that different observers record the same behavior similarly.
• B. It measures how consistently an observer records the behavior across trials.
• C. It provides evidence that different observers agree on what was counted.
• D. It verifies the social validity of the intervention.

Answer: (C)

Interobserver agreement shows that more than one observer records the target behavior in the same way. Its main purpose is to provide evidence that different observers agree on what was counted, which supports the reliability and credibility of the data. When observers independently apply the same operational definitions and tally the same events, we can trust that the measurement is not biased by a single observer’s judgment.

For example, if two observers watch a session and both count how many times a child emits a request, high agreement means they’re interpreting and recording the behavior consistently. This helps ensure the data reflect actual behavior rather than a single observer’s perception or error, and it also indicates that the observation procedures and definitions are clear and well-trained.

While intraobserver consistency (one observer’s consistency across trials) is about one person, interobserver agreement specifically addresses multiple observers agreeing on what was counted. Social validity relates to the acceptability and relevance of the intervention, which is a different consideration.