Authors:

Stevic, A., Chen, Y.A., Lee, A.Y., Smith-Russack, Z., Cairns, K., Kahl, B., Nicholas, M., Hall, I., Tharmakumar, T., Carlson, B., Coudhury, M.D., Etchells, P., Keyes, K., ORBEN, O., Prinstein, M., Robinson, J., Sawyer, S., Sefton-Green, J., Third, A., Werner-Seidler, A., Hancock, J.

Reference:

Year of publication:

In Press

CBU number:

9286

Abstract:

Introduction Australia implemented the Online Safety Amendment (Social Media Minimum Age) Act 2024 (Cth ; SMMA) on December 10, 2025. This policy represents a world-first social media age-restriction, which requires age-restricted social media platforms to take reasonable steps to prevent Australians under the age of 16 from creating or keeping an account. Preliminary estimates suggest that approximately 1,194,000 young people should be affected by the deactivation of accounts. As the SMMA is enacted, we are collecting data to examine the outcomes for young people, parents, and families. This study protocol paper serves as a summary of the methodological design for the evaluation of the implementation and outcomes of the SMMA, including a) young people’s adherence , and the SMMA’s impact on b) their digital practices, c) their physical, psychological, and social wellbeing, d) their families, and e) community attitudes and dynamics. Methods and Analysis To evaluate the impact of the SMMA implementation, a mixed-methods approach is being undertaken involving 4,121 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 (e.g., multi-level modeling, 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 inferences 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 wellbeing 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.