Socioeconomic status indexAn exploratory factor analysis (EFA) was used to create an index of socioeconomic status using the psych package (version 2.1.3) in R (version 4.0.4). The variables entered into the EFA included:(1) Highest level of education completed (secondary education [e.g., GED/GCSE], high school diploma/A-levels, undergraduate degree [BA/BSc/other], graduate degree [MA/MSc/MPhil/other], doctoral degree or higher).(2) Occupation (full-time student, never worked/long-term unemployed, consultant, skilled labourer, trained professional, support staff, administrative staff, junior management, middle management, upper management).(3) Key worker status (yes, no).(4) Relative income (continuous).(5) Subjective social status (working class, lower-middle class, upper-middle class, upper-class).The following EFA analyses were conducted using guidelines outlined in Preacher and MacCallum (2003). Bartlett's test indicated correlation adequacy, ꭓ 2 (10) = 204.02, p < .001, the KMO test indicated sampling adequacy, MSA = 0.67, and the determinant (|R| = .544) was well above the specified cut off of .00001, suggesting that the data were not multicollinear. As that dataset that underwent EFA included a mix of continuous, polytomous and dichotomous variables, the mixed.cor function from the psych package was used to calculate the correlation matrix that was subjected to EFA.It is important to use multiple methods to determine how many factors to retain (Harrison, 2020). Here, parallel analysis, scree plot examination, and the K1 criterion (Kaiser, 1974) were utilised. The K1 criterion, scree plot and theoretical assumptions suggested that a one factor model was appropriate. However, the results of the parallel analysis suggested two-factors. Therefore, taken together, a one-factor model was tested. The scree plot and parallel analysis are shown in Figure S1.