“…This is also reflected by the slight surplus of predominantly normative studies (56%) based on mathematical modelling (64% proportionately) [2,6,10,33,34,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. Whereas two studies pursue a purely qualitative approach [20,55] and six are purely conceptual [56][57][58][59][60][61], eleven studies employ a combination of several approaches [4,14,33,35,37,39,40,41,48,51,62] and three are based on panel data [3,31,63]. As already indicated, our search strategy was directed at studies that explicitly focus on the actual (investment) decision, i.e., phase 4 in Straub and Welke's risk planning model [14].…”