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CHAPTER 1 - Text Analysis (part VI)

Equivalent classes and Relations graphs

For the graph display, you can choose between the following modes: [Actors], [Area], [Star], [Distribution] or [Episodes]. Use the context menu that appears when clicking on an object of the graph with the right button of the mouse.

The reference graphs (area and star) show the Relations between the Equivalent classes. They are oriented: the classes on the left of the central class are its predecessors, those on the right its successors.


The first graph displays the classes in the form of Areas:

Text Analysis graphs

Each Equivalent class appears as a sphere, whose surface is proportional to the number of words it contains.

The distance between the central class and the other classes is proportional to the number of Relations connecting them: in other words, when two classes are close together, they share many Relations, and when they are far from one another, they share few Relations.

If we take up the metaphor about the planetary system, we can say that there is a central body (Equivalent class), around which planets (Equivalent classes having Relations with the central class) of various sizes (according to the number of word occurrences they contain) revolve more or less closely (are more or less frequently used together).

Notes:

1 - The overlapping of two spheres has no particular significance.

2 - Word categories cannot be displayed in the area mode.

3 - When the display is focused on the top of the ontology of a Scenario, Tropes evaluates the Relations of the graph by counting all the items in the selected branch. This is only an approximation of variables that are not independent. But it avoids empty graph display and provides useful information on this branch of the ontology.


The Graph of the actors represents the concentration of relations between the main actors (actants/acted) in the whole of the text. It can be used to make a visual comparison of the "weight" of the Relations between the principal references (or between the groups in the Scenario).

The references are displayed along two axes:
1 - the X axis (horizontal) shows the actant/acted ratio (from left to right).
2 - The Y axis (vertical) shows the concentration of relations for each reference displayed (strong at the top of the graph, weak at the bottom).

The concentration of relations is calculated, for each reference, by dividing the total number of relations by the number of different relations. Since Tropes V8.1, the result is weighted by the logarithm of the frequency of occurrence (that gives more weight to frequent references).

The lines show the relations between the reference selected and the other references displayed. A dotted line shows an infrequent relation. A solid line indicates a frequent relation. This graph can show two networks of relations: the selected class and the one pointed by the mouse. If you click on the bottom of the graph, all relationships are displayed.

The example below is taken from the analysis of the UNICEF (United Nations Children's Fund) "Plan of Action in 1990". The most frequent reference (child) has been selected.

Text Analysis graphs

In this example, the software has positioned the principal concepts (woman, education, action, etc.) at the left (actants with a high concentration of relations), while the secondary concepts are positioned either at bottom left (actants with a low concentration of relations) or on the right (acted). Most of the other references are acted (on the right).

The frequency of relations and the number of different relations are indicators of the centre of interest of the text analyzed. If the author, or authors, of the text have associated a reference with many other references, it may be deduced that this reference is very important, or at any rate more important than others. On another level, this new graphical representation shows an overall graph, not depending on the selected reference alone (as is the case with the star and area graphs).


The Star graph displays the Relations between the Equivalent classes, or between a Word category and an Equivalent class:

Text Analysis graphs

In the above example, the "liberty" semantic class (central point) is preceded by the "right", "human rights", etc. classes. On the right are many successors to "liberty": "declaration", "opinion", "difference", etc.

The figures shown on the graph give the number of Relations (co-occurrence frequency) existing between the various Equivalent classes.

You can follow the Relations shown on the graph by clicking directly on the classes you wish to study. This very powerful function enables you to move through a text while viewing its micro-worlds and analyzing the connections between its various actors.

When you use the [Relations] command of the Result frame, the graph reveals two central classes:

Text Analysis graphs

In this example, we can see that there is only one Relation leading from the "dictatorship" class to the "human rights" class, whereas there are two Relations leading from the "liberty" class to the "declaration" and "opinion" classes.


The Distribution graph enables you to display a histogram showing the distribution of an Equivalent class, of a Relation (i.e. between two Equivalent classes), or of a Word category:

Text Analysis graphs

In the above example, we can see that the "Education" Equivalent class appears rather at the end (right side) than at the beginning (left side) of the text.

This graph is obtained by splitting the text into several sectors containing the same number of words, and by calculating the occurrence frequency of the selected Equivalent class within each sector. The histogram bars present each sector in chronological order, from the left (beginning of the text) to the right (end of the text). The dotted line indicates the average size of the histogram bars.

When clicking on a given bar, the display will automatically position itself on the propositions appearing from this point of the text onwards. To return to the standard display, make a second click on the same bar. When pointing at a given part of the histogram, the message line displays the number of words contained by the selected sector, as well as its place (beginning and end of the sector, calculated in number of words from the beginning of text).

The number of histogram bars and the sum of words contained in each bar are automatically determined by the software according to the total of words in the text, and to the size of the main window.

When the distribution graph concerns a Relation, the histogram gives the accumulated occurrence frequencies of the classes contained in the Relation.


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