Abstract: Focusing on the question of how a firm in supply chain indirectly shares the product quality information via its CSR strategy,a supply chain consisting of an upstream supplier,a downstream retailer and final consumers is considered. In this supply chain,the supplier owns private information on the product quality level and tries to signal it by its CSR strategy and the supplier and the retailer transact via a wholesale price contract. Under this quality information asymmetry,in order to examine the role of CSR on signaling the quality level and the profitability conditions for the implementation of CSR mean,a signaling model is built to capture how the supplier indirectly share the quality information by its CSR strategy,the pooling equilibriums in the model when implements no CSR and the separate equilibriums in the model when implements CSR strategy are completely characterized,and a unique equilibrium is selected by the intuitive criterion. The equilibrium results show that under some technical conditions,(1) a high enough CSR level signals a high quality level in the sense of a separate equilibrium,(2) the equilibrium with the lowest threshold of CSR level is the only equilibrium satisfying the intuitive criterion,(3) the lowest threshold of the equilibrium CSR levels increases in the low-quality supplier's CSR efficiency,but is independent of that of the high-quality supplier,and (4) when and only when the differences between two types of suppliers' CSR marginal cost are sufficiently small,it is profitable for high quality supplier to share quality information through the CSR mean. These results reveal a quality-signaling motivation of firm's CSR strategy in a supply chain,provide supply chain managers indirect methods on sharing product quality information except the existing direct way,with an implication on choosing a direct or an indirect way to sharing information conditional on a known cost of direct information sharing.

Key words: corporate social responsibility, product quality, signaling game, supply chain