Developing causal loop diagrams (CLDs) involves identifying stakeholders and endogenous variables and formulating variable causal relationships. Traditionally, the CLDs are developed mainly using a qualitative approach such as literature review, observations and interviews with stakeholders. However, modellers may question which stakeholders should be approached, whether the relevant variables are selected, and what to do when stakeholders perceive different variable relationships in the CLDs differently. Applying in a case study, this research proposes a multi-method approach by combining both quantitative and qualitative methods to select stakeholders, identify endogenous/exogenous variables, and develop the CLDs. The proposed quantitative method is expected to provide modellers with a justifiable stakeholder and variable selection process. The method also highlights possible hidden variables and relationships, which were further explored with a traditional qualitative approach.

Previous research regarding PhD students’ well-being (PhD-WB) has lacked a comprehensive and systemic analysis. This research engages with a systems approach to examine the multiple variables, including feedback mechanisms, which influence PhD-WB over time. The model was developed using a structural analysis method (Cross-impact analysis MICMAC) that informed a causal loop diagram (CLD). The aim was to understand what promotes (drivers) and inhibits (barriers) PhD students’ well-being. The results show that PhD students’ well-being reflects an interplay between university, financial support, students’ mental and physical health, and family/friends. However, the analysis shows that the role of the drivers is dynamic, and they can become barriers in certain circumstances. This insight validates the application of systems thinking to illustrate the complexity of PhD students’ well-being.

This Evidence Snapshot is a July 2020 updated rapid review of knowledge about the use of masks by asymptomatic people to reduce transmission of COVID-19, the original review having been completed in April 2020. The updated review found that, while the evidence was limited and of low certainty, wearing masks in community settings is likely to reduce transmission of COVID-19. Some peer-reviewed studies included other protective measures in their scope, and thirteen of the twenty-eight recommended using masks in combination with these other measures. Where supply of masks is limited, higher risk individuals or residential areas with high transmission rates should be prioritised. A total of fifty-one articles were reviewed: 28 peer reviewed studies and 23 commentary articles and agency reports, with 31 of these articles being new in the updated report.