Reproducible ≠ Robust: Why One UMAP Seed Isn't Enough to Trust a Split
Pinning random_state=42 makes a UMAP-based train/test split perfectly reproducible — and that is exactly why it can lull you into a false sense of rigor. Reproducibility guarantees you get the same answer every run; it says nothing about whether that answer is typical. Here's the distinction, why it matters for evaluating GNNs on chemical-domain shifts, and how to fix it.
Jun 23, 2026