The intraclass correlation coefficient (ICC) is a statistical measure used to assess the reliability or consistency of measurements made by different observers measuring the same quantity. It evaluates how much of the total variance in the data can be attributed to differences between the subjects being measured, rather than differences between the observers or measurement methods. ICC values range from 0 to 1, where a value closer to 1 indicates high reliability and consistency among the measurements. It is commonly used in fields such as psychology, medicine, and education to ensure that data collected from various sources is dependable and valid for analysis.