【正文】 irst demonstrated the effect of customer retention on firm profits, researchers have made substantial progress in understanding the mechanics of customer defection. Recent studies have provided insights into defection processes (Keaveney 1995), consumer profiles of switchers (Ganesh, Arnold, and Reynolds 2021。 a phenomenon often attributed to “technophobia” (Reed 2021。 Heide and Weiss 1995。 Dwyer 1997。 What is the True Value of a Lost Customer? Customer profitability models have evolved into an important strategic tool for marketers in recent years. The authors show that conventional models may be inappropriate for markets involving new products or services because they fail to account for the social effects (., wordofmouth and imitation) that can influence future customer acquisitions. They develop a customer profitability model that captures these social effects and show how the value of a lost customer depends on (a) whether the customer defects to a peting firm or disadopts the technology altogether and (b) when the customer disadopts the technology distinctions often overlooked in customer retention models. An empirical application of the model to the online banking industry shows that the financial impact of disadoptions can be substantial. The results demonstrate that firms suffer financial losses not only when their own customers disadopt a new service or product, but also when their petitor’s customers disadopt. By incorporating the effect of petitors’ disadopters into the customer profitability model, the authors identify a heretofore unrecognized link between a firm’s market share and customer profitability. In addition, the model enables the firm to quantify the value of a lost customer throughout the product lifecycle with the results demonstrating that the loss of an early adopter costs the firm much more than the loss of a later adopter. Results also suggest that managers must pay greater attention to postpurchase service strategies early in the productmarket evolution to minimize the effect of disadoption on future customer acquisitions. An appealing aspect of the proposed approach is that it can be implemented using a spreadsheet, making it a practical tool that can help firm’s manage their customer relationships more profitably. INTRODUCTION Consider the following scenario. Joan has heard a lot about wireless webenabled cell phones recently from friends and through magazine and television ads. After several weeks of deliberation, she decides to add the service to her existing mobile phone service to access the web and check while away from home. After a few months, she starts to use it less and less until she eventually puts it aside and cancels her service subscription. What is the financial impact on the seller of Joan’s decision to disadopt webenabled cell phone service? Conventional customer profitability models would attribute the lost profit to the value of Joan’s potential product upgrades, service contracts, software, and accessories that she might purchase in the future. Yet, such an approach would significantly underestimate Joan’s value to the firm. Had Joan continued to use the service, she would have influenced potential customers to switch from basic cell phone service to webenabled service each time she used it public or wondered aloud how she ever managed to live without it. In other words, focusing only on the “direct effect” associated with the profits from Joan’s future purchases overlooks the “indirect effect” that Joan’s wordofmouth, imitation, and other social effects have on future sales. As we show in this research, the profit impact of these “l(fā)ost” social effects can be substantial. In recent years, customer profitability models have evolved into an important strategic tool for managers in a variety of markets. If such models are to guide marketing strategy decisions, however, they must account more pletely for the way that innovations affect the social interactions of current and potential customers. Theoretically, these interactions represent an important link between the retention of current customers and the acquisition of future customers that has not been adequately explored by researchers. How can social effe