## 5 Conclusions  
### Theoretical Implications  
This study explored the attribute bidirectional performance by dividing online reviews into positive reviews and negative reviews. The Kano-IPA model was used for further understanding of customer's rating behaviors and demands for hotel service. The proposed methodology in five phases of sentiment analysis and Kano-IPA model enriches the research on online hotel reviews. The main theoretical contributions introduced are as follows:  
First, this study explores the well-performed attributes contributing to high customer ratings and the poorly performed attributes causing low customer ratings. By dividing 1,090,341 online reviews into positive and negative reviews, the six attributes' good performance (positive sentiment values) in positive reviews and poor performance (negative sentiment values) in negative reviews are calculated through sentiment analysis. Our findings suggest that room, cleanliness and location are the most crucial determinants of both high and low customer ratings for hotels of these four levels. By contrast, other attributes, including value, service and sleep quality, have less impact on customers' rating behaviors. Therefore, the most crucial hotel attributes influencing customer satisfaction and dissatisfaction are exactly the same. Focusing on improving service quality of these general attributes including room, cleanliness and location is the key to win high customer ratings for all hotels. Thus, the effect of good/poor performance concerning location, value, service on high/low customer ratings varies across hotel star ratings. Second, comparative analysis of attribute bidirectional performance concerning four hotel star ratings was conducted to verify the difference of hotel attributes contributing to high/low customer ratings among different hotel star ratings. This study indicates that the impact of several attributes on high/low customer ratings varies across different star hotels. On one hand, the impact of value and service's poor performance on low customer ratings varies across hotel star ratings. With the improvement in the hotel level, the impact of value's poor performance on low customer ratings shows a downward trend, while the impact of service's poor performance on low customer ratings shows an upward trend. For three-star and below hotels, value's poor performance contributes more to low customer ratings than service's poor performance. In contrast, for four and five star hotels, service's poor performance has greater impact on low customer ratings. On the other hand, the good performance in room, location, value, service and sleep quality contributes to high customer ratings differently among different star hotels, where the impact of value and service's good performance on high customer ratings shows a larger range of changes. Interestingly, for value and service, with the improvement in the hotel level, the impact of their good performance on high customer ratings shows the same trend as the impact of their poor performance on low customer ratings. These findings indicate that customers' expectations and perceptions on the good/poor performance of each attribute may vary across hotel star ratings. Thus, it is necessary to take hotel star ratings into consideration on customer satisfaction research. Third, this study suggests that the effect of good performance on high customer ratings may not be equal to the effect of poor performance on low customer ratings for the same hotel attribute. In other words, the effect of attribute performance on customer satisfaction is asymmetric. For this reason, the Kano-IPA model was applied to better understand customer's rating behaviors and demands for hotel service. The Kano categories of five attributes (location, service, room, cleanliness and sleep quality) vary across different hotel star ratings. Furthermore, suggestions on priority for attribute improvement are formulated for hotels of the four star ratings according to the results of Kano-IPA model.