STAR: a transposition of the PICO framework to environmental sciences, engineering and beyond

The formulation of research questions and the search of relevant bibliographical references are critical steps in the pursuit of evidence-based research. This process ought to be comprehensive, transparent, and reproducible. Furthermore, it must lead to the retrieval of a maximum number of potentially related articles that are subsequently analyzed to identify those that are effectively relevant. However, in environmental sciences, these tasks are often performed without an enabling systematic framework, but relying instead on an assembly of keyword strings and ‘regular expressions’ structured as a Boolean equation. This ad hoc approach often yields an incomplete and inconsistent search of the literature, which undermines the reliability of evidence syntheses. To address this gap, we introduce STAR, a System-Trouble/Treatment-Alternative-Response framework spun off the PICO (Population, Intervention, Comparison, Outcome) framework. STAR is well suited to perform evidence-based literature reviews in environmental sciences supported by robust bibliographical search strategies and research questions. In this paper, we detail the thinking process behind an effective application of STAR through several examples taken from different fields of environmental sciences and engineering (i.e., environmental informatics, hydroinformatics and sociohydrology, entomology and plant pathology, environmental sustainability, soil sciences, coastal sciences, and agrifood sciences).