The term "not provided" found in marketing analysis reports now accounts for nearly 40% of referring traffic data from organic search, up 171% since Google introduced the policy one year ago, according to a study released Tuesday. Some believe it will spur the use of ad retargeting and social media. Some 64% of companies analyzed in the study see between 30% and 50% of their traffic from Google as "(not provided)," and 81% see more than 30%, according to Optify's report, Google (Not Provided) On the Rise. The report details the impact of Google's SSL enhancements on SEO referral data collected by publishers. The study suggests that recognized referring keywords from organic search declined by 49%. Last year, Google gave signed-in search engine users an option to encrypt their search queries using Secure Socket Layer. The process encrypts Google search queries, meaning that data about visits from organic search queries no longer provides information, such as referring keywords, on each individual query. Rather than the exact word, Google began passing publishers the term "not provided" as the referring keyword for visits from search engine queries and clicks. Google's intent was to provide security and privacy, but it has had an alternative outcome. Doug Wheeler, CMO at Optify, said "our No.1 keyword term is 'not provided.'" The landing site still receives information that a site visitor came from Google, but the encrypted search terms are excluded from the referrer headers as part of the request sent to the result site visited. Wheeler believes the percentage of "not provided" data will grow — and it will force brands to do more retargeting. Marketers may need to develop other metrics to confirm performance. In the long term, it means marketers will not have the option of measuring performance of SEO efforts by connecting a search term with Web site metrics like traffic, conversion rate, leads, engagement, and revenue. The Optify report also suggests marketers will no longer have the ability to use referrer data to customize and personalize the experience for site visitors. For example, don't bother using referring keywords in lead nurturing rules, or score visitors and leads based on their referring keyword. Optify analyzed the organic traffic to 424 business-to-business (B2B) Web sites between Nov. 1, 2011 and Oct. 1, 2012, tracking 17,143,603 visits from organic search -- an average of 1,428,634 visits per month. During that time, the company captured 7,241,093 referring keywords.