Question: Which of the following is true about interobserver agreement? A. IOA assesses new staff competence and identifies observer drift, B. IOA should be collected for a minimum of 20% of sessions, C. IOA confirms the changes in data reflect changes in behavior, or D. All of the above. And the correct answer is, D. All of the above.

First of all, IOA assesses a new staff member’s competence. When you have large discrepancies, we have to investigate the reason, and often what that leads us to is finding issues in the performance of a staff person or maybe they’ve got some abilities in data collection that need a little more support and a little more training. Similarly, IOA identifies observer drift. Now, these are unintentional changes in the understanding of what the operational definition is. If you’ve added something to the operational definition, or you took something out of the operation operational definition, inevitably there’s going to be discrepancies between observers, as evidenced in the IOA, the percentage of agreement. When IOA meets that minimum 80% criterion, what this does is increases our confidence that the definition of the target behavior was clear, and both observers are on the same page. Similarly, it could decrease our confidence if the agreement is low. IOA helps us to believe that the data variability is not due to the person recording the data, and therefore supports our belief that the changes in data actually reflect changes in behavior.

Now there are a few IOA rules to live by. First of all, the measurement system has to be the same for all observers and the observers have to measure the same behavioral events. Observers also have to record their data independent of each other. That means you can’t engage or collaborate with each other. The old, you know, “Hey, what did you get for that last interval?”. Nope, you cannot do that.

IOA has to be reported in percentage. Percentage data is how we display or explain the agreement. And this has to be done for a minimum of 20% of sessions during each phase of a study. It’s also recommended that IOA recording sessions are distributed right across days of the week, times of the day, settings, and observers.

There are some options in the way that we report IOA. Narratively, is the most common and easiest. All that you would do in the narrative format is basically report the mean or the range of the agreement percentage. But you can also display it on a table or a graph if you want to get a little bit fancier. Obviously, the perfect agreement would be 100%; that would be ideal. But, good news, we will settle for just 80%. And here’s the bad news, there are nine IOA formulas. You have to memorize all nine because you never know what’s going to be on your actual exam.

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Validity

Measurement is trustworthy when the measurement that produces data is applicable and specific to the target behavior of interest and the relevant dimension of that behavior; in other words, you…

Reliability

Measurement is trustworthy when the degree to which repeating a measurement procedure under the same conditions produces the same result.

Reactivity

Refers to the changes in an individual’s behavior due to the presence of an observer.

Observer drift

When observers collecting data have a shift/drift in how they interpret the operational definition of the target behavior that affects the validity of their data.

Observer reactivity

When an observer’s data collection or performance is influenced by the awareness that they are being monitored and evaluated.

Measurement artifact

Data that represents an unwarranted and misleading picture of behavior because of how it was measured, typically a product of time-sampling, limiting measurement scales, or poorly scheduled measurement periods.

Measurement bias

When an observer’s measurement is influenced by an expectation or belief they hold rather than what actually occurred.

Interobserver agreement (IOA)

A measurement of the degree to which two or more observers report the same values when observing and collecting data for the same behaviors/events.

Accuracy

The degree to which what was measured (observed value) is representative of what actually occurred (true value); in other words, the data was measured correctly.

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