On testing structural identifiability by a simple scaling method: Relying on scaling symmetries can be misleading

Alejandro F Villaverde; Gemma Massonis

doi:10.1371/journal.pcbi.1009032

On testing structural identifiability by a simple scaling method: Relying on scaling symmetries can be misleading

PLoS Comput Biol. 2021 Oct 14;17(10):e1009032. doi: 10.1371/journal.pcbi.1009032. eCollection 2021 Oct.

Authors

Alejandro F Villaverde¹, Gemma Massonis^{2

3}

Affiliations

¹ Universidade de Vigo, Department of Systems Engineering and Control, Vigo, Galicia, Spain.
² Universidade de Vigo, Department of Applied Mathematics II, Vigo, Galicia, Spain.
³ Bioprocess Engineering Group, IIM-CSIC, Vigo, Galicia, Spain.

Abstract

A recent paper published in PLOS Computational Biology [1] introduces the Scaling Invariance Method (SIM) for analysing structural local identifiability and observability. These two properties define mathematically the possibility of determining the values of the parameters (identifiability) and states (observability) of a dynamic model by observing its output. In this note we warn that SIM considers scaling symmetries as the only possible cause of non-identifiability and non-observability. We show that other types of symmetries can cause the same problems without being detected by SIM, and that in those cases the method may lead one to conclude that the model is identifiable and observable when it is actually not.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Computational Biology / methods*
Models, Theoretical*

Grants and funding

AFV has received funding from a Ramón y Cajal Fellowship (RYC-2019-027537-I) and from the Spanish Ministry of Science, Innovation and Universities and the European Union FEDER under project grant SYNBIOCONTROL (DPI2017-82896-C2-2-R). GM was funded by the CSIC intramural project grant MOEBIUS (PIE 202070E062). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.