["Health Expectations, Volume 29, Issue 4, August 2026. ", "\nABSTRACT\n\nBackground\nPatient and public involvement and engagement (PPIE) is vital for good‐quality health research. However, PPIE is more commonly practised in some types of research than others. Statistical methodology research aims to improve the way we design studies and analyse data. It can be particularly challenging to involve members of the public and patients in this type of research because the work can be technical and difficult to explain. Consequently, PPIE work typically requires considerable time and resources. Our previous research suggests that most statistical methodologists do not feel confident in carrying out PPIE for statistical methodology research and would benefit from access to new guidance and training.\n\n\nMethods\nThis qualitative, ethnographic study will combine observations and interviews to generate new insights into what works well, and what the challenges are, when involving the public in statistical methodology research. Data will be analysed using the template approach and presented in composite case studies, generating an interactive guidance document for researchers and PPIE groups to support the practice of impactful PPIE in statistical methodology research.\n\n\nDissemination\nWe will hold a virtual launch event for the co‐produced guidance and case studies. These will be made freely available on a dedicated website and Learning for Involvement, and highlighted via social media. The work will be presented at key conferences and published in open‐access peer‐reviewed journals. Findings will also be shared in educational resources to influence the next generation of researchers.\n\n\nPatient or Public Contribution\nThe study design has been informed by the perspectives of public co‐applicants on the grant. The research team will work alongside a public advisory group (PAG) consisting of six public contributors with extensive PPIE experience. The PAG will be chaired by Begum, a public co‐applicant. We will recruit three more public contributors to take part in online workshops to develop the main output of the study.\n"]