Kendall Tau is a statistical measure used to assess the strength and direction of association between two ranked variables. It evaluates how well the relationship between the variables can be described using a monotonic function. The value of Kendall Tau ranges from -1 to 1, where 1 indicates a perfect positive correlation, -1 indicates a perfect negative correlation, and 0 suggests no correlation. This measure is particularly useful in situations where the data does not meet the assumptions of parametric tests, such as normality. It is often applied in fields like social sciences, economics, and biostatistics to analyze ordinal data.