“…The independent variables used as control variables are chosen in accordance to the specifications of previous research on trust, the informal economy and informal payments for health services ( Balabanova and McKee, 2002 ; Szende and Culyer, 2006 ; Tomini and Maarse, 2011 ; Tomini et al, 2012a , b ; Baji et al, 2013 ; Kaitelidou et al, 2013 ; Tomini and Groot, 2013 ; Riklikiene et al, 2014 ; Arsenijevic et al, 2015 ; Danyliv et al, 2015 ; Stepurko et al, 2015 ; Williams et al, 2016 ; Ai et al, 2022 ; Horodnic et al, 2022a ) and include: age, gender, educational level, income, employment status, residence area (rural or village) (details in Table 1 ).…”