Word-of-mouth (WOM) marketing-firms' intentional influencing of consumer-to-consumer communications-is an increasingly important technique. Reviewing and synthesizing extant WOM theory, this article shows how marketers employing social media marketing methods face a situation of networked coproduction of narratives. It then presents a study of a marketing campaign in which mobile phones were seeded with prominent bloggers. Eightythree blogs were followed for six months. The findings indicate that this network of communications offers four social media communication strategies-evaluation, embracing, endorsement, and explanation. Each is influenced by character narrative, communications forum, communal norms, and the nature of the marketing promotion. This new narrative model shows that communal WOM does not simply increase or amplify marketing messages; rather, marketing messages and meanings are systematically altered in the process of embedding them. The theory has definite, pragmatic implications for how marketers should plan, target, and leverage WOM and how scholars should understand WOM in a networked world.

The growing amount of electronic word of mouth (eWOM) has significantly affected the way consumers make purchase decisions. Empirical studies establish an effect of eWOM on sales but disagree on which online platforms, products, and eWOM metrics moderate this effect. The authors conduct a meta-analysis of 1532 effect sizes across 96 studies covering 40 platforms and 26 product categories. On average, eWOM is positively correlated with sales (.091), but its effectiveness differs across platform, product, and metric factors. For example, the effectiveness of eWOM on social media platforms is stronger when eWOM receivers can assess their own similarity to eWOM senders, whereas these homophily details do not influence the effectiveness of eWOM for e-commerce platforms. In addition, eWOM has a stronger effect on sales for tangible goods new to the market, while the product life cycle does not moderate the eWOM effectiveness for services. With respect to the eWOM metrics, eWOM volume has a stronger impact on sales than eWOM valence. In addition, negative eWOM does not always jeopardize sales, but high variability does.Keywords: electronic word of mouth, online reviews, online ratings, online platforms, social media, eWOM metrics, eWOM volume, eWOM valence, eWOM variance, bandwagon effect, persuasion effect, meta-analysis Aloe, Ariel M. and Cristopher G. Thompson (2013), "The Synthesis of Partial Effect Sizes,"

Word-of-mouth (WOM) marketing-firms' intentional influencing of consumer-to-consumer communications-is an increasingly important technique. Reviewing and synthesizing extant WOM theory, this article shows how marketers employing social media marketing methods face a situation of networked coproduction of narratives. It then presents a study of a marketing campaign in which mobile phones were seeded with prominent bloggers. Eightythree blogs were followed for six months. The findings indicate that this network of communications offers four social media communication strategies-evaluation, embracing, endorsement, and explanation. Each is influenced by character narrative, communications forum, communal norms, and the nature of the marketing promotion. This new narrative model shows that communal WOM does not simply increase or amplify marketing messages; rather, marketing messages and meanings are systematically altered in the process of embedding them. The theory has definite, pragmatic implications for how marketers should plan, target, and leverage WOM and how scholars should understand WOM in a networked world. Marketers and sociologists have recognized the importance of the phenomenon of word of mouth (WOM)-conceptualized as a naturally occurring phenomenon-for more than half a century, proposing, for example, that WOM affects the majority of all purchase decisions (Brooks 1957; Dichter 1966). However, these theories and observations about informal, unsolicited WOM were con- The Internet's accessibility, reach, and transparency have empowered marketers who are interested in influencing and monitoring WOM as never before. This article is situated firmly within this new marketing reality. We offer theory that integrates these transformations into the world of WOM. We begin with an overview of the development of WOM theory and its assumptions, placing recent developments into historical context. Building on this framework, we detail our empirical investigation of an online WOMM campaign that engaged consumers who were seeded with a new technology device to generate WOM in their personal blogs. Our findings specify how this marketing process unfolds in the realm of consumer-to-consumer WOM communications. We discuss both theoretical and managerial implications. KeywordsWe discover and demonstrate four distinct blogger communication strategies in response to the product seeding. These communication strategies are marked by the prominent tension between commercial and communal norms. In addition, they are shaped to fit the represented individual blogger narratives. These communication strategies have specific implications for how marketers should leverage WOMM campaigns, both online and offline. The Transformation of WOM TheoryAs markets change, marketing theories must also change to accommodate them. In this section, we provide an assumptive frame for this article by briefly reviewing the develop-

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A key issue for marketers resulting from the dramatic rise of social media is how it can be leveraged to generate value for firms. Whereas the importance of social media for brand management and customer relationship management is widely recognized, it is unclear whether social media can also help companies market and sell products. Extant discussions of social commerce present a variety of perspectives, but the core issue remains unresolved. This paper aims to make two contributions. First, to address the lack of clarity in the literature regarding the meaning and domain of social commerce, the paper offers a definition stemming from important research streams in marketing. This definition allows for both a broad (covering all steps of the consumer decision process) and a narrow (focusing on the purchase act itself) construal of social commerce. Second, we build on this definition and develop a contingency framework for assessing the marketing potential that social commerce has to offer to firms. Implications for researchers and managers, based on the proposed definition and framework, are also discussed.