Click-through rate (CTR) is a metric used in information retrieval (IR) to measure the effectiveness of search results in engaging users. It is calculated by dividing the number of clicks on a search result by the number of times the result was shown (impressions). For instance, if a search result was shown 100 times and clicked 10 times, the CTR would be 10%.
CTR is crucial for evaluating the relevance of the results presented to the user. A higher CTR indicates that users are finding the search results relevant, whereas a lower CTR may suggest that the results do not meet users' expectations. This metric is commonly used to optimize the ranking algorithm of search engines, ensuring that more relevant documents appear at the top.
In IR, CTR is frequently used in A/B testing to compare different versions of search algorithms. By analyzing changes in CTR, developers can assess which algorithm better serves the user's intent and refine the search engine’s performance accordingly.