Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Gavagai Explorer is a tool to analyze related texts to find common topics, their associated terms, their sentiment scores and their prevalence in the data (number of respondent mentions). Although the primary use case for Explorer is the analysis of open-ended survey responses, it can be used to analyze any set of related texts such as product reviews, Net Promoter Score programs, or social media opinions for a given target-of-interest.

...

This documentation introduces the main features of the Gavagai Explorer and guides you through using these features effectively.toc


1 Introduction

All of Gavagai's services are built on top of a core system called the Gavagai Living Lexicon, which continuously learns languages by ingesting newly published texts from the Internet. Through this process the lexicon learns about the vocabulary of the language and the relationships between words and multiword expressions. From this understanding we can extract useful information in our services. For more information about the Living Lexicon's website.

...

You need to create an account with the Gavagai Explorer before you can start to analyze your texts.To get a free trial account, open this link in your browser: https://explorer.gavagai.se, click the ‘Try for free’ button and follow the instructions.

...

You first need to specify the main text column that you want to explore. Note that if your file consists of more than one text column you are interested in exploring, you need to create a separate project for each of these columns. You also need to choose the language of your texts. When you select the text column, Explorer flags the language automatically.

2.3.1 Applying a Template Model – Optional

You can apply a model as a template to your project. In chapter 8 we explain how models are created and used in Gavagai Explorer.  

2.3.2 Filter Conditions by Meta-Data – Optional

You may optionally set up some filtering conditions on values from other columns than your main text column. In the drop-down menu you will find those columns that are candidates for filtering - this means those columns that have a few different values repeated over and over, like ratings, or gender. Then you can choose which values are accepted for that column. After choosing the accepted values, save your settings by clicking on the ‘Add filter’ button.

...

When Gavagai Explorer completes analyzing your data at each iteration, it presents the result in a GUI (Graphical User Interface). The GUI is divided into three main sections. At the top of the GUI you can find the configuration panelwhere you can apply a template model to your project, set up filtering conditions and remove terms from your analysis. Under the configuration panel, on the left, we have the working panel where you can interact with the system and your data. Finally, on the right we have the Details Panel where you can see the results of your analysis with details.

3.1 GUI Main Buttons

3.1.1 The Undo and Explore Buttons

The Gavagai Explorer GUI has two important buttons that you need to use continually when analyzing data with the Explorer. They are the ‘Undo’ and ‘Explore’ buttons. If you know how to use these buttons correctly, it will help you to analyze your data with Explorer more easily. The ‘Undo’ button can be found at the top of the working panel. For ease of access, the ‘Explore’ button has been placed in three different areas of the GUI; at the bottom of the configuration panel and at the top and bottom of working panel. Note that the functionality of all three of these buttons is the same.

...

When you make changes in the working panel and before you press the ‘Explore’ button, Explorer will keep track of the current changes and provide you with an ‘Undo’ button that can be used to reverse changes in sequence. Keep in mind that you cannot automatically reverse the changes once you have pressed ‘Explore’ and moved on to the next iteration.

3.1.2 Pin Button

For each topic in the working panel, we have a pin button which is specific to that topic. When you pin a topic by pressing this button you tell Explorer that you want to keep it in the list of the topics regardless of its frequency. This is particularly relevant when you filter texts, remove terms or add data. Other important applications of pinning are when you create models from your existing projects (see chapter 8) or when you export the result of your analysis in a full MS Excel format (9.1 Save as Excel and Full CSV).

Explorer will also provide Theme Wheels for your 6 most frequent pinned topics (6 Explorer Theme Wheels).

3.1.3 Topic Scroll Button

For each topic we have a topic scroll button in the working panel (see the previous picture). When you press this button the Details Panel will automatically scroll to the selected topic.

...

In the following, we explain the main elements in each topic and we guide you through revising them.

4.1 Terms in Explorer

4.1.1 An Introduction to Explorer language Capabilities

4.1.1.1 Paradigmatic Neighbors

Explorer searches for terms in your data with more complexity than a simple search engine. Let us explain by an example. Consider the word “income” in the following sentences:

...

In the first two sentences, income has been referred to as a general term while in the two latter sentences the terms gross income and net income are specific types of income. In the last sentence, the word income is not present, but we have the word compensation which is a synonym of it. Words like income, net income, gross income and compensation are called paradigmatic neighbours. Paradigmatic neighbours are semantically related words which are used in text or speech for related objectives. Paradigmatic neighbours can be synonyms, like “income” and “compensation” in above examples. They can also be words that do not have same meanings but they are related in some way; e.g. “fork” and “spoon” which are both used for eating.

4.1.1.2 N-grams

An n-gram is a sequence of words which frequently appears in the same order in text or speech. Generally, it is important not to split n-grams as it might result in information loss. For instance, “water supply” is an n-gram consisting of two words “water” and “supply” while none of these words can define it individually. The word “San Francisco” is an n-gram which is different from both “San” and “Francisco”. Another capability of Explorer is to identify n-grams in your data and not split them. From now on, when we mention terms in this document we mean n-grams. The value of variable n is dependent on the corresponding language and it is usually between 1 and 3 or more.

4.1.2 Terms and suggestions

As mentioned, each topic can include one or more terms. Terms included in each topic are words that each can define that topic independently. Each term can belong to only one topic. For each topic, Explorer shows examples of texts including the terms in that topic. You can find them in explorer Detail panel. You can also filter the examples by clicking on specific term(s).

For the terms included in a topic, Explorer automatically finds their paradigmatic neighbours and shows them to you as Suggestions. You can see more suggestions by clicking on Get More button (figure to be added). When you hover over a suggestion in the working panel, a question mark will appear. You can see the examples of the texts including that suggestion by clicking on this question mark.

4.1.3 Adding and Removing Terms

4.1.3.1 Adding Terms

You can always expand your topics by adding new terms to them; either from Explorer suggestions or as your own input. To add terms, you need to open terms and suggestion by clicking on topic expander. Then you can write your terms in the text box and click on Add words. You can also search for terms in the same text field. The search has auto-complete capability. You can also add terms by accepting suggestions from Explorer. To see more suggestions, you can click on Get More button. 

...

In this case, if you choose to accept compensation for the topic income, Explorer will merge the two topics automatically (read more about merging in 5.2.3 Merging Topics). This is basically because the terms in each topic are assumed to be synonyms (so if two terms in two different groups are synonyms then all terms in that groups are synonyms). In figure below you can see the new topic income after automatic merging. The topic compensation will become disabled. The next time that you press Explore, you will see the new statistics for the new topic income and the topic compensation will be removed from the list.

4.1.3.2 Sticky Synonyms

When you accept a suggestion for a topic in a project, the connected terms are saved in your account (sticky synonyms), and they are automatically applied in new projects; which means the previously accepted suggestions are automatically added in your new project.

4.1.3.3 Removing Terms

You can remove terms from topics by clicking on them in the working panel. When you remove a term, you might still see it in the list of suggestions of other topics and therefore you can add it to them. Note that when you remove a term from a topic, Explorer automatically pins that topic so that you would not lose the topic in the list of topics in case the topic becomes infrequent.

...

For any subset of the set of terms and associations of a topic, you can filter the texts examples that contain all the words in that subset. You only need to click on them in the detail panel to filter texts.

4.3 Sentiment Analysis

Gavagai Explorer applies word based or lexical based sentiment analysis principles to quantify the sentiments behind expressed opinions. In the Details Panel, you can see the quantity of three basic sentiments for each topic or group; that are Negativity, Positivity and Skepticism (next figure). When you filter texts by selecting terms and associations in the details panel, the sentiment values will be updated as well. When you export the result of your analysis into excel, you can see 8 sentiment values for each single text (see 9.1.2 Sentiments). You can also select one or multiple topics for sentiment analysis when you export. This will give the sentiment scores for your selected topics in the report (see 9.1.5 Sentiments Per Topic). Moreover, you can model your own sentiments by using Explorer Concept Modeler and then Explorer will analyze your data for these Concepts (read more in 7 Explorer Concept Modeler).

...

Explorer performs two different types of sentiment analysis; new and classic sentiment analysis. Explorer selects the new sentiment algorithm by default. You can switch to the classic sentiment algorithm in Account Settings located in My Account page. The Explorer will strictly apply only one algorithm for the entire Explorer project. When you set an algorithm for your account, you must click Update and Save to apply the new algorithm.

The classic sentiment algorithm performs a sentence level sentiment analysis for each topic. The new algorithm performs a topic level sentiment analysis for the topics. More on both of these algoriths in 4.3.4 The Sentiment Analysis Algorithms that Determine the Score.

...

The system's sentiment scoring gives a score for each Sentiment word used to describe a topic. Note, amplification words such as "very" increase the score. And negations such as "not" impact the score by reducing the score.

...

The room was not good. Has a 1 for Sent: Negativity.

There are eight sentiment categories: Skepticism, Fear, Violence, Hate, Negativity, Love, Positivity, and Desire. The categories avoid ambiguity of sentiment scoring by not containing words that can be inside many categories. For example, "cheap" could have different sentiments. For example, "X is cheap". This sentence is ambiguous. If X is beer, it is positive, if X is a wedding ring it is negative. Thus, if there is a word that you believe should be in the sentimental category then please try to use the word in sentences that are both that sentiment and the opposite sentiment to check. In contrast, words such as "good" that express only one sentiment are added to their respective sentiment category.

When a word from the eight categories like, Positivity, for example "good" is used to describe a topic such as hotel. The sentiment score will give a simple 1 for the topic hotel. The sentence, "The hotel is good." would receive a 1 for positivity, and 0 for the seven other sentiment categories. If you would like to see the actual numbers for the sentiment scores for each topic, you need to export the analysis as an Excel or CSV file and select the topic you would like to see. See 9.1.5 Sentiments Per Topic for more. The sentiment score given for each topic varies when combination of words happen such as "really good".

...

In the web application the sentiments are in the right hand side with a percentage breakdown. We see the sentiments Negativity, Skepticism, and Positivity in a bar. This sentiment percentage bar is calculated by using the topic that the percentage bar is referring to. All the topics' Positivity, Negativity, and Skepticism scores are summed. Then, each of Positivity, Negativity, and Skepticism scores are divided by the sum to return a percentage.

4.3.4 The Sentiment Analysis Algorithms that Determine the Score

Consider the following text uploaded to The Explorer:
  • The room was good and the staff are bad.


The text include two different topics and for each topic there is a different opinion. The new sentiment algorithm has more precision in getting the expressed opinions for individual topics and calculating the sentiment scores. The room topic has a 1 for positivity. And the staff topic has a 1 for negativity. Looking at the web application there is 100% positivity for room and 100% negativity for staff.

Moreover, for the new sentiment algorithm, not all topics are relevant for sentiment analysis. Explorer only performs sentiment analysis for topics (or topic terms) that are not sentiment terms themselves.

Consider the sentence "The room is nice". If we ask what is the expressed opinion about room in this sentence, one can say it is positive, it is nice. Now suppose that instead of room we focus on nice as a topic. Does it make sense to ask "what is the expressed opinion about nice in this sentence"? The answer is no. In fact nice is not a focus topic in this sentence. The sentence is explaning room and not nice. Nice is the word by which the sentence expresses opinion about room. This is the reason behind why we do not perform sentiment analysis for sentiment terms.


The classic algorithm takes into account sentimental words of an entire sentence. Regardless of what topics the sentimental words are describing. For example, the sentence, "The hotel was good and the staff are good." will return a 2 for positivity for the topic hotel and the topic staff. Thus, there is less percision in analyzing the sentiment. In addition, for the web application, the detail panel will only display sentiment when 10 texts have sentiment for a topic.

The sentence uploaded as an excel file to The Explorer (repeated 10 times since we need at least 10 texts):
  • The room was good and the staff are bad.


returns for the topic room, 1 for Positivity and 1 for Negativity. And in the web application, we see the topic room have 50% Negativity and 50% Positivity. This is a coarse approach and can be inaccurate in calculating sentiments for topics.

However, there are some benefits. The classic algorithm is useful for calculating what the sentiment is on a sentence level is. Which is important for comparing individual documents. In addition, there is a slight speed advantage.

4.4. More about n-grams in Explorer

Now that you have learned about topics, topic terms and sentiment analysis, it is worth learning a bit more about n-grams in Explorer as well. As mentioned before, n-grams are topic terms including multiple words, for example "San Francisco".  Explorer identifies n-grams in your data and show them to you as topics if they are enough frequent. You can also add n-grams to your topics manually. The most important characteristics of the n-grams is that they are treated as one single entity, and therefore, the uni-grams included in an n-gram cannot contribute to topics individually. This is the case for both topic counts and sentiment analysis. As an example, suppose that you have an n-gram "junk food". Also assume that you have a topic FOOD which includes "food" as a topic term but not "junk food" as a topic term. Now for the sentence "I don't like junk food at all", for Explorer the topic FOOD is not included in this sentence because of "junk food" being a bi-gram. 



5 Revising Topics

In this section, it is explained how to revise your topics by Explorer according to your assumptions and needs.

5.1 Adding and Removing Topics

5.1.1 Adding Topics

You might be interested in specific topics which are not frequent enough to appear in the list of topics. You can add these topics to your project manually and Explorer will analyze your data for themwith a semantic search.

You can add topics by clicking on the Add Topic button in the top of the working panel. When you click on this button, Explorer considers a new topic area for it at the top of the list. Here you can give a name to your topic, and you can add terms to your topic by writing them in the text box and clicking on Add words. When you are done, click on Remove me after adding words.

Note that the name of the topics are only labels that are assigned to them, and therefore each topic should have at least one term. Terms are the exact words the Explorer actually keeps track of in your data. You cannot add a term which is already included in another topic. The new topics are automatically pinned, so Explorer keeps them in the list regardless of their frequency.  

Keep in mind that Explorer does not add these new topics to your analysis until you have pressed the 'Explore' button.

When you add new topics to your project and press Explore, Explorer starts re-analyzing data and it inserts new topics into the list of topics in order of their frequency. Then, you can see the information about associations, suggestions and statistics for new topics.

Note that Explorer does not remove any topics from the list when you add new ones.

5.1.2 Removing Topics

You can also remove a topic from your analysis if you find it unimportant for your project. Hover over that topic in the working panel and click on cross button to remove the topic.

Explorer will ignore the topic when you remove it from the list, however, note that texts including that topic are still available for inclusion in other topics. The terms including in each topic are saved in configuration panel under the Ignored Terms, and you can have them back at any point by clicking on them.

5.2 Grouping and Merging Topics

5.2.1 Select button

When you hover mouse over a topic in the working panel, an upwards arrow appears inside the topic box which is called Select button. You select a topic by clicking on this button. When the topic is selected, the topic blue box turns to orange. You can also deselect the topic by re-clicking on this button.

In Explorer, both merging and grouping should start with selecting a topic. In the following it is explained how we can merge and group topics by Explorer.

5.2.2 Grouping Topics

5.2.2.1 Intro

If you find some topics to be in the same category you can put them in one group. This will give you a more organized working panel. In addition, Explorer will tell you about the sentiment and statistic of the whole group.

For instance, for the hotel reviews, you might like to put all the words about food (e.g. breakfast, coffee, wine, etc.) in one group called Food. Explorer shows you the number of the respondents that have written about food (frequency of the whole group). It also shows you the aggregate sentiments of this group, so it wil let you know if the respondents are positive or negative about food on the whole.

5.2.2.2 How To Group

Grouping topics in Explorer starts with selecting one single topic by clicking on Select button. When you click on this button, a down arrow button will appear in the left side of each topic or group. We refer to this button as Group button. You can place the selected topic into a target group by clicking on this button. By default, the name of the group will be the name of the target topic (or group). You can change this name by re-writing it in the working panel.

5.2.2.3 Statistics

After re-exploring data by Explorer, grouped topics are inserted into the list of the topics in order of their aggregate frequency (which is the number of distinct texts that include at least one of the topics divided by the whole number of topics). This value can be found in both working and detail panel under the group name. In the detail panel and under each group name, you can also find the aggregate sentiment of that group. The frequencies, sentiments, associations and suggestions for single topics can be found under their names like before.  

5.2.2.4 How to Ungroup

You might want to take a topic out of a group. You can click Undo button at the top or click the ungroup button. Note that the topic you ungroup from a group will be automatically pinned. You should update and save after.


5.2.3 Merging Topics

5.2.3.1 Intro

In case that you find two topics equivalentyou can merge them to one single topic. This is mostly the case if the terms in two topics are synonyms or paradigmatic neighbors. For instance, for two topics income and compensation including the terms income and compensation successively, you might merge them to get a single topic including both the terms income and compensation. Merging topics increases the strength of the resulting topic in terms of the number of texts that are included in the topic and therefore it results in preciser sentiments and more informative associations.

5.2.3.2 How to merge

Similar to grouping topics, merging topics starts with selecting a single topic. As before, you select the topic by clicking on the Select button in the topic box. When the topic is selected, an upwards arrow button will appear at the left side of all other topics. We call this button as Merge button. You merge the two topics by clicking on the Merge button for the second topic. By default, the name of the merged topic will be the name of the first selected topic. You can change this name by re-writing it in the topic box.

6 Explorer Theme Wheels

As mentioned before, Explorer represents an statistical visualization of your first 6 pinned topics (or groups) by Explorer theme Wheels. At the top of each theme wheel, you can find the name of the corresponding topic. The frequency of the topic can be found in the center of the wheel. The pieces of the wheel are the four most frequent associations of the topic. If you hover over a piece you can see the frequency of the corresponding association inside the topic.

Here you can see the theme wheel regarding the topic “room” in hotel reviews. The topic has a frequency of 75.4% in the data and its most frequent associations are “great”, “clean”, “comfortable”, and “staff” respectively. The frequency of “great” as an association of “room” is 39.8%. This means that almost 40% of the people who have mentioned room in their responses have found it great.

7 Explorer Concept Modeler

Concept Modeler is a tool for additional analytics in Gavagai Explorer. You can define different concepts in Explorer and then analyze you data with respect to them. Same as models, concepts are independent from projects and one concept can be used in different projects. A concept is defined by its including terms. In contrast with topics, the including terms in a concept do not need to be synonyms or semantically similar terms, but they are elements that jointly define that concept. Let’s give an example.

In Hotel Reviews you might define a topic called breakfast, including the terms “breakfast” and “the breakfast”. Each of these terms that appear in a text we will know that the topic breakfast is included in the text. Now consider the two following sentences retrieving from texts:

  • They had excellent organic coffee available in the lobby.

  • I enjoyed starting the mornings with cinnamon latte and croissant.

None of the words “coffee”, “latte”, “croissant” or “mornings” can define the topic breakfast independently; as the case in the first sentence, but a combination of these words can tell us that the text might be related to the concept breakfast; as the second sentence.  

Therefore, the concept breakfast can be defined by set of words like {tea, coffee, latte, bread, cheese, jam, morning,...}. You can start defining the concept by a few most necessary words. Then Explorer will show you more suggestions to be added to your concept. When you save your project as Full Excel or Full CSV (see 9 “Save as” Button and Exporting the Result of your Analysis), Explorer analyzes your data with respect to your target concepts, and tells you the number of present terms relating to each concept for each text. It will also provide sentiments scores related to your target concept.

7.1 How to Create, Edit and Use Concepts

To start creating a new concept or editing the old ones, you can click on My Concepts in Explorer navigation bar to be redirected to concepts page. In this page you can see the list of all of your concepts that you have previously created. To create a new concept, click on Create concept button. You will be then redirected to your new concept’s page. Give a name to your concept by writing it in the “Concept name” text field and select the language of your concept. Add terms to your concept by writing them in “Keywords” text field and add them by pressing the add button. When you are done with adding the most necessary terms for your concept, press the Create Concept (and get suggestions) button to save your concept and get new suggestions.  

8 Models in Gavagai Explorer

You can save a project in Explorer as a model and then apply the model as a template for other projects. Using models is a suitable approach when you analyze similar types of data frequently and you have same concerns in your analysis; for example, you are looking for the same topics or themes. Here we explain models in Explorer and we guide you through creating and using them. However, if this is the first time that you are reading this document, we recommend you to skip this section for a little while and return to it after reading other parts of the document.

A model consists of your specific settings in a project; meaning grouped topics, merged topics, pinned groups and topics, and your ignored terms. When you apply a model on a project, the project current model will be replaced by the new one. Therefore, if you are unsure, you would better save the current model first.

Note that to apply a model to your project, the project’ file does not need to have the same specifications as the model’ source file (e.g. same columns or same number of texts, etc.).

8.1 Creating and Applying a Model in Explorer

8.1 Create Models from Projects

You can create a model from a project by selecting Model under Save as drop-down menu in the working panel.

8.2 Upload Models

You can also upload a model from your computer and use it in different projects. The Upload Model button can be found in My Models page.

8.3 Applying a Model to a Project

To apply a model to your project in Explorer, you can find the model under Apply the model drop-down menu in configuration panel. Another way of applying a model to your project is to find the ID of another project from the browser's address bar (the last segment in the URL), and enter it in the provided text field.

9 “Export as” Button and Exporting the Result of your Analysis

After each iteration and before you make any changes to your project, Explorer provides a Save as button where you can save the current result of your analysis in different formats. Under Export as drop-down menu there are 4 options; PDF, Excel, Full CSV and Model.

If you want to have a brief report of your analysis similar to what you see in Explorer GUI, you can save your project as either PDF or Excel. In case you want to have a detailed result of your analysis with respect to individual texts, you can choose Excel or Full CSV.

When you choose the format, a message box will pop up (next figure). You can either choose to be redirected to the project edit page where you can download your file or you can do it later by pressing Ok. The project edit page can be accessed from Explorer homepage (My Projects page) by clicking on Edit page button for that Project as on the figure below.

9.1 Save as Excel and Full CSV

When you download the result of your analysis as Excel or Full CSV, you will have a Excel or CSV file containing your original data appended by the analysis result from Explorer. Explorer performs a row based analysis of your data in respect to your pinned topics, target concepts and sentiments, and for each text it adds the result of the analysis to the corresponding row. In the following we explain the appended columns.

9.1.1 Pinned Topics

The first added columns are the columns regarding to your pinned topics. You can see the name of each pinned topic in a header of a column. A cell in a topic column contains 1 if the corresponding text includes that topic, and 0 otherwise.

9.1.2 Sentiments

The next added columns are the ones containing sentiment scores. Explorer measures 8 standard sentiments for each text; they are: SENT: DESIRE, SENT: FEAR, SENT: LOVE, SENT: POSITIVITY, SENT: SKEPTICISM, SENT: NEGATIVITY, SENT: HATE, SENT: VIOLENCE. You can see their names on the header of the columns. Each cell in a sentiment column contains the score of that sentiment for the entire corresponding text. In case you have selected a Target Concept for the analysis of your project, the sentiment scores will be restricted to the sentences that contain at least one of the terms in any of those concepts.

9.1.3 Target Concepts

The next columns are the target concepts that you have chosen to include in the report. For each target concept there is a column in the Excel file having the concept name in its header. Each entry in a concept column is the number of distinctive terms in that concept that are included in the corresponding text.

9.1.4 Keywords

The next columns in the report are the keywords columns. Keywords are those terms that best describe the subject of the texts. There are 4 different keywords columns in the Excel report:

  • The first column is “Keywords”. Explorer identifies the most significant keywords in each text and inserts them in the corresponding entry of this column in form of [keyword 1, keyword 2,…,keyword n] where the value of n can be different for different texts.

  • The second column is “Qualified Keywords”. Each entry in this column is a list containing those keywords from the previous column (means the “Keywords” column) that a Wikipedia page exists for them. Explorer considers these keywords as qualified keywords.

  • The third column is “Expanded Keywords”. Each entry in this column is a list containing the semantically similar words to the keywords of the corresponding text.

  • The fourth column is “Qualified Expanded Keywords”. This column contains those terms from previous column that have been qualified by Wikipedia as before.

  • The last column is “Summary”. This column contains the most significant sentences in the texts.

9.1.5 Sentiments Per Topic 

For a selected topic, you can gauge the sentiment in each individual text and add a column for each sentiment to the report. For instance, if you select a topic after clicking the Export as Excel or CSV dialogue box to bring up the Configure Report Box, each text in your project will be analyzed with respect to the Positive, Negative, and Skepticism sentiment around the topic, and the columns for the sentiment scores of the specific topic(s) chosen will be added to the resulting Excel file under the name Sent: Positivity(topic name).

This is useful when you want to compare the positive sentiment score of the verbatim – located in the usual column called SENT: POSITIVITY. With the topic's positive sentiment score – located in the new appended column called SENT: POSITIVITY (*what ever topic you chose*). For example, if your topic's positive sentiment score is very large and almost as large as your verbatim sentiment score. Then there is a strong indication that the topic is driving the positivity of the verbatim.

*note adding a lot of topics to analyze will add thee columns per topic. Thus, the report generation time will be affected, the more topics are selected.

The Sentiments per topic and per verbatim are used in the Driver PDF report. 

9.2 Drivers (PDF) – Satisfaction Drivers Visualization 

When you download the results as a PDF. You will get a X-Y Scatter plot with overall satisfaction on the Y axis, the driver satisfaction on the X axis. Each plot on the graph is a satisfaction driver that is a result from the text analysis which is a topic and their associations. The driver satisfaction score is from the sentimental analysis score of the topic and the association. The overall satisfaction score is the sentimental analysis score of the text where the topic and association appears. (See see 4.3 Sentiments Analysis.) The correlation is between the driver's satisfaction and the overall satisfaction of the text. Drivers with high correlation imply that they "drive" overall satisfaction. 

...