We propose a game‐theoretic approach to examine several possible coalition strategies in a four‐echelon supply chain consisting of a supplier, manufacturer, wholesaler, and retailer. A solitude model is used to probe the role of learning in quality improvements, and experimental design is conducted to evaluate all possible supply chain coalition strategies between echelons. The novelty of this study is the comprehensive evaluation of knowledge‐sharing strategies in collaborative supply chains. The results confirm that the Delta model with a coalition among a supplier, manufacturer, and retailer is the best strategy.