Impact of the Social Media Minimum Age on Australian young people and parents: protocol for a mixed-methods evaluation.

introductionAustralia implemented the METHODS AND ANALYSIS: To evaluate the impact of the SMMA implementation, a mixed-methods approach is being undertaken, involving 4121 young people aged 10 to 16 years and their parents or caregivers. Data collection involves five-wave longitudinal parent-child surveys, opt-in passive smartphone tracking, administrative linked and non-linked health and educational data, qualitative interviews and focus groups. We will conduct descriptive analyses examining frequencies, average values, percentages, factor analysis and reliability of scales for each survey wave. Various analytical approaches (eg, logistic regressions, multi-level modelling, random-intercept cross-lagged panel model) may be used to understand both between-person and within-person changes pre- and post-implementation of the SMMA. For causal inference analyses, we will employ targeted maximum likelihood estimation (TMLE) as our primary strategy to evaluate the effect of young people's adherence to the SMMA on key outcomes, such as psychosocial well-being and distress. Qualitative data will be analysed using a combination of thematic analysis and structured coding approaches. This will include iterative analysis of open-ended survey responses and in-depth qualitative data from interviews, focus groups and related tasks to identify key themes, patterns and lived experiences. ETHICS AND DISSEMINATION: The study received ethical approval from the Australian Institute of Family Studies (AIFS) Human Research Ethics Committee (application approval number 2025/06) and complies with the National Statement on Ethical Conduct in Human Research and the Australian Institute of Aboriginal and Torres Strait Islander Studies (AIATSIS) Code of Ethics for Aboriginal and Torres Strait Islander Research. All participants provided informed consent at the beginning of the baseline survey and in each subsequent wave. Only parents and young people who provided their consent were eligible to take part in the study. Findings from this evaluation will inform national policy oversight and implementation in Australia, contribute empirical evidence to international debates and inform other countries considering similar age-based regulation of social media. Results will be disseminated through public-facing reports, peer-reviewed publications and stakeholder engagement activities to support evidence-informed decision-making in digital safety regulation in Australia and internationally.