Fr\'echet Covariance and MANOVA Tests for Random Objects in Multiple Metric Spaces

Abstract

In this manuscript we consider random objects being measured in multiple metric spaces, which may arise when those objects may be measured in multiple distinct ways. In this new multivariate setting, we define a Fr\'echet covariance and Fr\'echet correlation in two metric spaces, and a Fr\'echet covariance matrix and Fr\'echet correlation matrix in an arbitrary number of metric spaces. We prove consistency for the sample Fr\'echet covariance, and propose several tests to compare the means and covariance matrices between two or more groups. Lastly, we investigate the power and Type I error of each test under a variety of scenarios.