\section{Conclusion}
\label{sec:conclusion}

This paper has built a reproducible pipeline from \nRecordsIdentifiedRaw{} bibliographic records to \nUsableEstimates{}
harmonised implicit prices from \nStudiesExtracted{} hedonic studies in \nCountriesExtracted{} countries, and has used it to answer
the questions the Sirmans programme posed in 2005 with the tools of 2026. The robust findings are few and clear. The structural
core of the hedonic model is global: living area, bathrooms, age and distance to the centre have implicit prices whose means are
precisely estimated and similar across continents and decades once the specification is controlled. The signature amenities
carry premiums of the order documented in the attribute-specific literature. Every implicit price is nonetheless heterogeneous
beyond sampling error, with prediction intervals that span zero for most characteristics, and the observable features of a
study, including the estimator, explain little of that heterogeneity. The tentative findings are the geographic and temporal
patterns, which are confounded by the composition of the literature; the publication-selection diagnostics, which are
suggestive for amenity premiums but not interpretable as corrections; and the AI evidence, which indicates better prediction
from tree ensembles and modest incremental information from text and image features in a small sample. The exploratory findings
are the machine-learning meta-regressions, which do not predict implicit prices out of study. The paper's contribution relative
to \citet{sirmans2005composition,sirmans2006value} is therefore a global, harmonised and uncertainty-aware restatement of what the
hedonic literature knows about the value of housing characteristics, together with a documented account of what it cannot know
until the literature reports its results in a form that can be accumulated.