08: Evaluating Search Engines 8. 1 Why Evaluate 8.2 The Evaluation Corpus 8.3 Logging 8. 4 Effectiveness metrics 8.5 Efficiency Metrics 8.6 Training, Testing, and Statistics 6/N08: Evaluating Search Engines 8.1 Why Evaluate 8.2 The Evaluation Corpus 8.3 Logging 8.4 Effectiveness Metrics 8.5 Efficiency Metrics 8.6 Training, Testing, and Statistics 6/N