When working with recommendations SharePoint 2013 Search records analytics events. By default those events don’t influence recommendations’ ranking.
When using search-driven content recommendations SharePoint 2013 records recommendation events such as which recommendations have been displayed and which of them have been clicked. By default those events only impact the relevance of content. Content that has been displayed as recommended content would become more relevant than content that hasn’t been used in recommendations. Additionally content recommendation that has been clicked on would become even more relevant than other content – recommended or not. Recommendation events have however no impact on the relevance of recommendations. In other words, content that has been previously recommended or event clicked on would not necessarily be recommended more often.