Better explanation of the number of topics and number of topics over time.

[Nikoleta-v3]

In your study, the appropriate number of topics was chosen based on the coherence value. Coherence indicates the possibility terms within a topic commonly appear together. However, there is also another commonly used indicator called exclusivity, which indicates the possibility the terms are exclusively related to the topic. Commonly, the two indicators will be used to select the best fitted model together. Hence, suggest adding it in your study, so to choose the appropriate number of topics by using both coherence and exclusivity.

Fifth, in page 9, the authors mentioned “The three models are LDA models for the entire data set for n equal to 5, 6 and the optimal number of topics over time,” it is not clear to me what do you mean by “the optimal number of topics over time.” How was it defined and calculated? Details should be provided.

Based on the first comment: We need to use another measure as well to make sure that n=5 is the best number of topics.