Kappa observed expected agreement is a statistical measure used to evaluate the level of agreement between two raters or judges based on categorical data. This measure is commonly used in fields such as healthcare, social sciences, and psychology to determine the reliability of measures and assessments.
To calculate kappa observed expected agreement, the observed agreement between raters is compared to the expected agreement that would occur by chance. The formula used to calculate kappa is as follows:
Kappa = (Observed agreement — Expected agreement)/(1 — Expected agreement)
The value of kappa ranges between -1 and 1, with a higher value indicating a stronger level of agreement between raters. A value of 1 indicates perfect agreement, while a value of 0 indicates agreement that is no better than chance. A negative value indicates disagreement between raters that is worse than chance.
Kappa observed expected agreement is particularly useful in situations where there are multiple categories or where the categories are subjective. For example, in a study measuring the reliability of a depression assessment tool, multiple raters may use different criteria to assign a diagnosis. Kappa observed expected agreement can help evaluate the level of agreement between the raters and determine the reliability of the assessment tool.
It is important to note that kappa observed expected agreement has limitations and may not always accurately reflect the level of agreement between raters. Factors such as the number of categories, the prevalence of each category, and the level of expertise of the raters can all have an impact on the kappa value.
In conclusion, kappa observed expected agreement is a valuable statistical measure for evaluating the level of agreement between raters or judges. It can help determine the reliability of measures and assessments and is commonly used in healthcare, social sciences, and psychology. However, its limitations should be taken into consideration when interpreting results.