## 3 Methodology
### Methodology for Post Collection and Annotation  
#### 3.1.1 Annotation Scheme and Key Definitions  
The main objective of the annotation scheme is to clearly define the elements of a post and the annotation procedure, so that the sentiment polarity of any target and/or emotion in a post can be assessed manually. We adopted [PERSON] and [PERSON]'s [20] proposition to define a post as a hex-tuple \((r,\,t,p,e,\,h,td)\), where \(r\) is a post, \(t\) is the target of the post \(r\), \(p\) is the polarity orientation of the post \(r\) in relation to the target \(t\), \(e\) is the emotion expressed in the post \(r\), \(h\) is the post holder of the post \(r\), and \(td\) is the time/date when the post \(r\) was expressed by \(h\). Target: in this annotation scheme, a target is defined as a tourism-related entity, which can be found in a post, such as a service, an attraction, an event, an organization, or a person. As a target can be a single or complex entity, we define a target as a pair, \(t\): (\(T\), \(A\)), where \(T\) is a hierarchical taxonomy of the target and \(A\) is a set of aspects/attributes of the target. If the target \(t\) is complex, its hierarchical taxonomy will contain sub-targets, i.e., \(T=<\)\(t_{1}\), \(t_{2}\),..., \(t_{n}\)\(>\), \(n\) is the number of sub-targets. If the target \(t\) has more than one aspect/attribute, then \(A=<\)\(a_{1}\), \(a_{2}\),..., \(a_{m}\)\(>\), \(m\): is the number of aspects/attributes. In our study, the target is tourism, and aspects are the most relevant tourism attributes, such as attraction, accommodation, food and beverage, weather, people and culture, transport, holiday in general, shopping and gift, and city facilities. In other domain-specific contexts, the annotation team can review the literature related to the domain context to identify targets and their hierarchy or use available ontology databases and semantic search engines for the task. Figure 1: Reviews along with their sentiments, targets, and aspects considered from SemEval-2016 Task 5. Opinion passage on a target or aspect: as a post \(r\) can comprise many sentences, we define the post as \(r=\textless_{1}\), \(s_{2}\),..., \(s_{k}\textgreater\), where \(s_{i}\) is the \(i\)th sentence in the post and \(k\) is the number of sentences. If the post r expresses different opinions on multiple aspects/targets, each sentence will be annotated individually in relation to the related target. Explicit and implicit opinion: a sentence that directly expresses a positive, negative or mixed (neutral) opinion is a subjective sentence with an explicit opinion. An implicit sentence indirectly implies an opinion and can be understood through the context of a whole post/sentence [36]. For implicit opinions, annotators interpret the posts, and the triangulation between the annotators is used to ascertain the target and its sentiment polarity. Sentiment polarity: this study adopts the ordinal sentiment classification system where polarity is quantified with an interval value to show the intensity of positivity or negativity, with the value 0 representing a neutral polarity. Two annotators manually assign a value between \(-5\) (negative) and \(+5\) (positive) to the polarity of each post as a whole and its meaningful sub-components. The annotators then discussed inconsistencies to reach an agreement. Finally, the average sentiment polarity is computed for each sentence and entire tweet. Emotion: emotion is a complex mental state which is difficult to measure. Tourism experiences are hedonic in nature, and emotion plays a pivotal role in motivating travel and influencing tourist satisfaction [45]. Conventional self-reported measures of emotion (e.g., emotional scales in a questionnaire) are common in marketing and tourism research. These measures tend to retrospectively assess consumer perceptions of emotions rather than capture emotions in real-time [45].