Background: Public involvement in research to improve data quality and to empower different stakeholders is good scientific practice, but rarely implemented across all research phases. Objective: This article reports on an attempt to involve members of a self‐help group for relatives of people living with dementia as co‐researchers in the data analysis in a short‐term format. Methods: One researcher identified statements about assistive technologies from 17 interviews with people living with dementia and informal caregivers. Two researchers and six co‐researchers independently assigned pre‐defined values to these statements. Subsequently, we compared the values of the researchers and co‐researchers. Results: The members of the self‐help group identified four original values not considered by the researchers: consent, inclusion, participation and respect. Discussion: The involvement of co‐researchers led to an improvement in the depth of data quality through the joint identification of values concerning assistive technology. Language barriers between researchers, co‐researchers and interview participants impeded the data analysis. Conclusion: The challenges and benefits of a participatory data analysis shown here can provide a basis for recommendations for target group‐specific research involvement. Our recommendations relate to the recruitment of co‐researchers, requirements for conducting a participatory data analysis and the participation degree of people involved. Patient or Public Contribution: The group of co‐researchers participating in the data analysis consisted of relatives of people living with dementia.