How to Calculate Intraclass Correlation Coefficient in Excel

What Is the Intraclass Correlation Coefficient?

The Intraclass Correlation Coefficient (ICC) determines the reliability of ratings for multiple items. The ratings are measured by comparing the variability of different ratings of the same item (or subject) rated reliably by different users.
The ratings are quantitative. The value of an ICC can range from 0 to 1, where 0 means no reliability and 1 means perfect reliability among raters.

The calculation takes into account the following:

Factors	Description
Model	One-Way Random Effects: This model indicates that each item is rated by a different group of randomly chosen raters. The raters are considered the source of random effects while using this model. As the same group of raters usually rate each item, so this model is rarely used in practice. Two-Way Random Effects: This model indicates that each item is rated by a number of randomly selected raters from a population. Both the raters and the subjects are considered the sources of random effects while using this model. When we want to generalize the findings to any raters similar to the raters used in the study, then this model is used. Two-Way Mixed Effects: This model indicates that each item is rated by a number of randomly selected raters from a population. The chosen group of raters are the only raters of interest for this model. So, we don’t want to generalize the findings to any other raters who share similar characteristics as the raters used in the study.
Type of Relationship	Consistency: The systematic differences between the ratings of judges. Absolute Agreement: The absolute differences between the ratings of judges.
Unit	Single Rater: When only a single rater is the base for the measurement. The Mean of Raters: When the mean of ratings from all the judges is the base for the measurement.

How to Calculate the Intraclass Correlation Coefficient (ICC) with Example

We have four different judges who rated the quality of 10 different products. The ratings are shown below.

Steps:

Go to the Data tab and select Data Analysis.

Selecting Data Analysis Tool to How to Calculate Intraclass Correlation Coefficient in Excel

A Data Analysis pop-up window will appear. Select Anova: Two-Factor Without Replication.
Click OK.

The Anova: Two-Factor Without Replication pop-up window will appear. In the Input Range box, drag through the whole range from your dataset that contains the rating values. For our sample, the range is C5:F14.
In the Output Range box, click on the cell in your dataset that you want as the starting cell of the output result. We selected cell H4.
Click OK.

Selecting Range for How to Calculate Intraclass Correlation Coefficient in Excel

You will get the outcome of the Anova: Two-Factor Without Replication in your worksheet.
You will be able to see the whole Summary of the calculations along with the individual Count, Sum, Average, and Variance of the ratings by the Judges for the Products.

Summary of How to Calculate Intraclass Correlation Coefficient in Excel

To measure the ICC based on those rating variations, you need the bottom Anova table for input values.
The formula to calculate the Intraclass Correlation Coefficient (ICC) for the extracted output is:

=(K26-K28)/(K26+J27*K28+(J27+1)*(K27-K28)/(J26+1))

Result of How to Calculate Intraclass Correlation Coefficient in Excel