اندازه گیری اعتماد بیش از حد به تصمیمات مدیریت موجودی  Measuring overconfidence in inventory management decisions

1. Introduction Today’s purchasing professionals have to handle complex environments and turbulent markets and often are asked to take decisions under conditions of increasing uncertainty (Harland et al., 2003; Wagner and Neshat, 2010). Recent literature has shown that – under these conditions, individual cognition and personality attributes of the decision maker may become crucial in determining outcomes (Ancarani and Di Mauro, 2011; Bendoly et al., 2010, 2006; Gino and Pisano, 2008; Loch and Wu, 2008; Lu et al., 2015). Findings gathered from diverse disciplines, such as economics, finance and management have emphasised the relevance of one particular individual bias, namely overconfidence, as a determinant of individual decisions in complex and uncertain environments (Camerer and Lovallo, 1999; Hayward et al., 2006; Li and Tang, 2010; Malmendier and Tate, 2005; Shipman and Mumford, 2011). Overconfident individuals tend to believe that their information or their estimates are more accurate than they actually are, or that they hold superior skills and abilities than average (Moore and Healy, 2008). Uncertainty may encourage overconfidence because decision makers misunderstand the hazards they face (Kahneman and Lovallo, 1993; Park and Santos-Pinto, 2010), or because it provides more room for discretion (Li and Tang, 2010). Overconfidence has been shown to result in poor performance in different decision contexts. In particular, empirical evidence suggests that overconfidence negatively affects judgment and decision making of managers (Aspinwall et al., 2005; Åstebro et al., 2007; Shipman and Mumford, 2011), leading to over-trading behaviour in the stock market (Odean, 1998), use of more long-term, as opposed to short-term, debt (Ben-David et al., 2007), imprecision of forecast (Hribar and Yang, 2011), and excessive risk taking (Li and Tang, 2010; Simon and Houghton, 2003),