Visualizing the social aspects

The dataset used for the visualization of the social aspects is multivariate, composed of

• date: Dates of the course, which started on 15/01/2002 and finished on 11/04/2002, making a total of 87 days. The dates have been mapped to the integer range[1, 87].

• student id: The students who participated in the course. There are a total of 17 students plus the instructor. They have been mapped to the integer range[1, 18] to reflect an alphabetical order, and the instructor has been assigned to the last number of the range.

• topic: The range of topics on which a discussion thread can be initiated. There are a total of 16 topics, which have also been mapped to the integer range[1, 16].

• follow up: It is a scalar that reflects the length of a discussion thread, i.e., the num-ber of replies a posted message has received.

The file reflects the data from a discussion board which allows the students to post messages to it. A message is composed of a sender, date, and a topic. The number of replies to a given message is called follow-up and it is expected that this value reflects the relevance of a given message. Figure 7.16 shows how the variates have been mapped onto the n-dimensional Window tool.

The visualization goals involving the behavioural aspect illustrate Scenario 1 of the investigation scenarios (described in Chapter 5, Section 5.3). In the situation described by Scenario 1 the user knows what to look for (the students’ participation in discussion forum and group activities) and where to find it (this information can be obtained from the cell that involves the students, message topic, and date of posting).

Figure 7.16: Mapping the variates’ labels of the social dataset to the axes of the n-dimensional Window tool.

Figure 7.17 presents a 3D scatterplot visualization corresponding to cell-(date, stu-dent id, topics). The spheres’ attributes, i.e. size and colour, are both mapped so as to

reflect the follow up values. The goal of this visualization is to follow both SR1 and SR2 recommendations (c.f. Subsection 7.3.3.2), that suggest showing the participation of students in the discussion forum and group activities, respectively.

Figure 7.17: Visualization of cell-(date, student id, topics) using a 3D scatterplot. The spheres represent the number of messages posted by the students throughout the course.

The size and colour of spheres have been mapped to reflect the number of messages (variate follow up).

A top view ofcell-(date, student id, topics) provides a better overview of the commu-nication activities that happened during the course duration, as shown in Figure 7.18. This visualization informs that the course has had a fairly large number of messages posted which might be regarded as an indicator that a good degree of communication has been achieved. However this could only be confirmed upon a qualitative analysis of the mes-sages’ content.

In the next pair of visualizations the n-dimensional Window has been used to separate the communications related to the units of the course (Figure 7.19-(a)) from the commu-nications related to the groups activity (Figure 7.19-(b)). The separation is accomplished by restricting the values of the variate topics on the n-dimensional Window diagram.

Notice in picture (a) of Figure 7.19 that there has been a fairly large amount of com-munication within each group. This visualization allows us to understand the message

Figure 7.18: Top view of cell-(date, student id, topics) shown in Figure 7.17. This view shows the variate date (horizontal axis) and variate topics (vertical axis). Labels on variate topics help the association of the spheres with their meaning.

(a)

(b)

Figure 7.19: Further visualization of cell-(date, student id, topics) (top view). In picture (a) only the messages within the groups have passed through the filter; while in picture (b) only the messages related to the units have passed through the filter.

responding to the Group04 (shown by a blue arrow in Figure 7.19-(a)) we could verify that these observations represent messages with no reply, i.e. the members of that group have not used the message board to communicate to each other. Finally picture (b) shows that the communication has been steadily developed throughout the course duration. In par-ticular, no messages have been posted on the topic “Unit 0” – indicated by a line with no spheres on it; and the “Unit 2” has had the longest discussion thread, spread out through a longer period of time than the other units – indicated by the longest horizontal sequence of spheres that contains the largest purple sphere.

Looking at the same cell from a different angle, as shown in Figure 7.20, allows us to have an overview of the messages posted by individual students. This is important because the instructors need to be able to measure the level of participation of individual students and this is exactly what this new viewpoint can provide.

Figure 7.20: Side view of cell-(date, student id, topics). In this view the variate date is the horizontal axis and the student id corresponds to the vertical axis.

The individual profile of the students can be generated again through the manipulation of the n-dimensional Window diagram so that a restriction is imposed on the student id variate. This can be done either by creating multiple filters (each one isolating a spe-cific student) or by using the NDNavigator to accumulate all the successive selection of students made with the help of the n-dimensional Window diagram and then using the NDNavigator to browse them.

A quick inspection of Figure 7.20 indicates that Francesco (student id = 7) was the stu-dent who has posted the greatest number of messages, followed by Massimo (stustu-dent id

= 11). Indeed a further investigation (i.e. isolating each student at a time) has revealed that Francesco posted 16 messages, whereas Luigi (student id = 9), Michele (student id = 12), and Nino (student id = 13) posted no messages at all. Figure 7.21 shows a visualiza-tion that combined the results from two filters that have been set up to isolate the students Francesco and Massimo.