1 INTRODUCTION  
1.1 Goals of this survey  

2 VARIOUS NLG TASKS  

3 HUMAN EVALUATION OF NLG SYSTEMS  
3.1 Human Evaluation Setup  
3.2 Criteria Used for Evaluating NLG Systems  

4 TAXONOMY OF AUTOMATED EVALUATION METRICS  

5 CONTEXT-FREE METRICS  
5.1 Untrained Metrics  
5.2 Trained Metrics  

6 CONTEXT-DEPENDENT METRICS  
6.1 Untrained Metrics  
6.2 Trained Metrics  

7 STUDIES CRITICISING THE USE OF AUTOMATIC EVALUATION METRICS  

8 EVALUATING EVALUATION METRICS  
8.1 Correlation Measures  
8.2 Significance Tests  
8.3 Issues and Influence of the Data and Human-Evaluation Setup  
8.4 Methods to Evaluate Robustness of Metrics  

9 RECOMMENDATIONS (POSSIBLE FUTURE RESEARCH DIRECTIONS)  

10 CONCLUSION