Hierarchical Permutation Tests for Functional Measurement Invariance

Provides a suite of functions to test for Functional Measurement Invariance (FMI) between two groups. Implements hierarchical permutation tests for configural, metric, and scalar invariance, adapting concepts from Multi-Group Confirmatory Factor Analysis (MGCFA) to functional data. Methods are based on concepts from: Meredith, W. (1993) ,5 Yao, F., Müller, H. G., & Wang, J. L. (2005) , and Lee, K. Y., & Li, L. (2022) .