# Enhancing Recommender System with Collaborative Filtering and User Experiences Filtering
## 6 Case of Study
### Validation  
Two aspects were validated: user satisfaction with the system and the precision of the recommendations. A precision measure based on user satisfaction was used to evaluate the received recommendations (Equation (5)), where \(t\) is the number of recommendations with a user satisfaction value\(>\) 4 and \(n\) is the total number of recommendations made.  
Validation of the overall performance of the system was carried out using the Technological Acceptance Model (TAM)method [31; 32; 33]. The TAM model is used to validate the adoption of technology by users. This model serves to predict the use of a technology based on two main features: (1) perceived utility (PU) and (2) perceived ease of use (PEU). PU refers to the degree of performance improvement in a task when using the system. PEU is the degree of user effort required to perform tasks.  
In this study, TAM was used to measure the degree of acceptance that users had with regard to the recommendations and the way in which they were presented. A questionnaire was designed to evaluate the performance of the proposed system according to the TAM method. The questionnaire and the results, summarized for each question putto the 70 participants, are presented in Table 5.  
Figure 2: Recommended hotel and relevant sentences from user feedback.  
The Cronbach Alpha coefficient was used to measure the reliability of the TAM method [33; 34; 35]. Cronbach's alpha is an index of internal consistency that takes values between 0 and 1 and verifies whether the instrument that is being evaluated collects defective information, which would lead to wrong conclusions. [PERSON]'s alpha is calculated using Equation (9).  
\[\alpha=\frac{K}{K-1}\left[1-\frac{\sum i}{Vi}\right] \tag{9}\]  
where \(\alpha\) is the alpha of Cronbach, \(K\) is the number of items within the criterion to be evaluated, \(i\) is the variance of each item and \(Vi\) the total variance. Good reliability is indicated with a value >0.70. The Cronbach coefficient for the survey was 0.9798. From this value, we can confirm that the questionnaire was reliable, that is, it effectively measured what it intended to measure. Next, [PERSON]'s alpha was also calculated for each of the criteria of the TAM method separately. Alpha = 0.9592 was obtained for PU, and Alpha = 0.9875 was obtained for PEU. These values allowed us to ensure that results of the questionnaire based on the TAM method were correct.  
The results of the validation show that, in general, users were very satisfied with the proposed system, i.e., 100% of users rated the system interface, navigation and structure favorably. However, three users noted that the query criteria were not sufficient. The reasons described by them were that it was necessary to apply an advanced search mechanism with some other criteria. The current query only allowed users to enter text with the name of a city or country where they wanted to travel. Regarding the most important functionality of the system, i.e., providing recommendations with information associated with the experience of other users, this was rated as satisfactory by the majority of users. Four users were not satisfied with the received recommendations. They argued that the recommended hotels did not meet their preferences. When analyzing this problem in more detail, it was observed that they had interacted with the system once, and the system did not have information to obtain more precise preferences.