Placebo analysis for causal inference in tourism

This paper proposes a structured framework for implementing placebo tests as diagnostic tools to assess the robustness of empirical analyses in tourism research. Building on the taxonomy of Eggers et al. (2024), we distinguish between treatment, outcome, and population placebos and translate these categories into a practical checklist that guides researchers from clarifying assumptions to designing suitable placebo scenarios. To illustrate the approach, we reconstruct and reanalyze the relationship between Blue Flag eco-labels and international tourism flows to Italian coastal provinces. The example does not aim to generate new substantive insights on eco-labels; rather, it demonstrates how placebo tests can be embedded within a transparent and systematic procedure to evaluate the credibility of estimated effects. By offering a step-by-step guide and an applied illustration, the paper encourages a more disciplined, transparent, and methodologically informed use of placebo tests in observational tourism research.