“…In particular, the characteristics used to identify reference groups vary: studies have used the average income or predicted income of reference groups based on individual characteristics such as age, gender, marital status, number of children, education, occupation, and industry (McBride, 2001;Senik, 2004;Ferrer-i-Carbonell, 2005;Luttmer, 2005;Senik, 2008;Caporale et al, 2009;Oshio et al, 2011;Brown et al, 2015;Goerke and Pannenberg, 2015;Welsch and Kühling, 2015). Additionally, different levels of spatial categories have been employed to construct measures of RI (Kingdon and Knight, 2007;Knies, 2012;Brown et al, 2015).…”