Lost in Translation: Harmonizing Terminology and Defining Mathematical Tools for Panel Optimization.

Abstract

Spectral flow cytometry has evolved from a contentious idea into a mainstay of high-parameter single-cell analysis, yet its vocabulary (and the statistical reasoning behind it) remains a patchwork of overlapping, sometimes contradictory terms. This position paper highlights the terminological fragmentation and translation gap, and aims to harmonize the field's lexicon while providing a cohesive information-theoretic framework for panel optimization. We expose the limits of popular ad hoc heuristics, matrix condition numbers, and pairwise cosine similarities, and promote stronger surrogates: effective rank and information efficiency, which together capture spectral independence and numerical stability, and the Cramér-Rao lower bound (CRLB) matrix, which directly predicts fluorochrome-specific spreading error. Building on this foundation, we revive the optimal-design criteria: D-optimality maximizes total information; A-optimality minimizes the average parameter variance; E-optimality constrains worst-direction inflation. By aligning precise definitions with actionable design rules, we provide a roadmap for consistent terminology, next-generation panel construction, and objective instrument benchmarking.