“…A central alternative to defining interest groups based on their lobbying function is to focus instead on a narrower definition that sees organizational characteristics as key defining features and reserves the interest group term for membership-based organizations (for example, Thomas and Hrebenar, 1990;Jordan et al, 2004;Halpin, 2006Halpin, , 2010Christiansen, 2012;Jordan and Greenan, 2012;Binderkrantz et al, 2014). 1 Some of the studies within this approach derive from a theoretical interest in the dynamics of group membership and mobilization -namely, when and how certain interests are mobilized into groups capable of politically relevant action (for example, Schlozman and Tierney, 1986;Walker, 1991;Jordan and Greenan, 2012).…”