It makes sense to get women to talk about brands, as brand reputations are increasingly formed on social media. A new study by marketing agency Haygarth has quantified the value of word of mouth among women. Haygarth head of planning Anthony Donaldson says US surveys have found women control around four-fifths of all spending decisions, so persuading them to pass on their endorsements to others could be crucial to brands’ fortunes. According to Haygarth’s study, incentives such as free trials and promotions are important cues for recommending brands, as is the quality of the product.