Adolescence Across the Mobile–Social Convergence

Adolescence Across the Mobile–Social Convergence: A Historically Positioned Multi-Domain Population-Profile Study with a Prospectively Frozen Third-Window Test This working paper examines whether adolescence exhibits a non-trivial multidomain reconfiguration across birth cohorts historically positioned at different stages of the transition to persistent, mobile, network-mediated social communication in Sweden. Rather than treating smartphones or social media as individual causal exposures, the study conceptualises mobile–social convergence as a transformation of the broader socialisation environment. Three birth-cohort windows are defined: 2000–2002, 2005–2007, and 2010–2012, with outcomes examined at approximately age 15 using harmonised publicly available Swedish population statistics. The present empirical analysis compares the first two historically positioned windows across multiple domains, including health and well-being, schooling, physical activity, social and relational behaviour, antisocial behaviour and victimisation, and digital sociality. The observed W1–W2 profile is treated as descriptive and hypothesis-generating rather than as an identified cohort effect or causal estimate of digital-media exposure. Period effects, including the COVID-19 pandemic, remain explicit rival explanations. The study uses a sequential open-science architecture separating source and variable specification, measurement harmonisation, raw evidence extraction, derivation, descriptive profile synthesis, interpretation locking, and prospective prediction. Following the W1–W2 analysis, explicit predictions and failure conditions for the third cohort window were frozen within the project before governed inspection of W3 outcomes. This Zenodo deposit provides the independent public timestamp for that frozen research state. The accompanying reproducibility package contains the governing protocol, raw evidence ledger, derived analytic dataset, harmonisation and derivation specifications, variable mapping, uncertainty metadata, descriptive interpretation lock, prediction eligibility and contamination registers, and the frozen prospective prediction registry required for later independent verification and W3 adjudication. The study does not claim that smartphones, social media, or mobile connectivity caused the observed differences. Its purpose is to determine whether historically differentiated adolescent populations exhibit a reproducible multidomain reconfiguration and to expose that proposition to a prospectively specified third-window test. Version: v1.2.1 Final Deposition BuildInternal freeze date: August 2026Deposit contents: Working paper; Research Contribution companion; curated reproducibility and prospective-verification package.