Ibaraki Prefecture
Covariance-Based Structural Equation Modeling in Small-Sample Settings with $p>n$
Hasegawa, Hiroki, Tamura, Aoba, Okada, Yukihiko
Factor-based Structural Equation Modeling (SEM) relies on likelihood-based estimation assuming a nonsingular sample covariance matrix, which breaks down in small-sample settings with $p>n$. To address this, we propose a novel estimation principle that reformulates the covariance structure into self-covariance and cross-covariance components. The resulting framework defines a likelihood-based feasible set combined with a relative error constraint, enabling stable estimation in small-sample settings where $p>n$ for sign and direction. Experiments on synthetic and real-world data show improved stability, particularly in recovering the sign and direction of structural parameters. These results extend covariance-based SEM to small-sample settings and provide practically useful directional information for decision-making.
TheGyro-StructureofSomeMatrixManifolds
In all cases, HypGRU achieves the best results when the data are projected to hyperbolic spaces before theyare fed to the network, and all its layers are based on hyperbolic geometry. Results of these networks are obtained using their official code.3,4 We also evaluate a light version of Shift-GCN referred to as Shift-GCN-light, where the numbers of inputand output channels for the input and residual blocks arereduced byafactor of2(thenumber ofinput channels fortheinput block is3). We can also see that whenM = 3, GyroAI-HAUNet outperforms Shift-GCN-light on all the datasets. Overall, whenM = 3, GyroAI-HAUNet is competitive to the best GNN model with far fewer parameters.