1. Guido Borà
guido.bora @ unisi.it
University of Siena
2013 Siena Workshop @ Rutgers

2. 04/05/2013
There is a considerable literature based on Social Networks sites
(SNs) where the objective is to study the effects of interactions
between users, for example friendship, classmate, roommate
and tastes. (Lewis and Kaufman et al. 2008) (Jaxkson and Pin et
al. 2009)
According to the seminal literature (Lazarsfeld and Merton
1954, McPherson et al. 2001) individuals with similar attributes
tend to end up together, this phenomenon is known as
homophily which is Summarized by the famous proverb "Birds
of a feather flock together".
These studies had the advantage of extracting hidden structures
and complex social ties however is still unclear, the cognitive
impact of communication in the interaction between individuals
(Chelmis and Prasanna 2011) and what is its influence on some
aspects of students' everyday life:
friendships, performance, sport and segregation of certain
minorities.
2013 Siena Workshop at Rutgers

3. 04/05/2013
» Organization of lotteries with rewards (beauty
contest and quizzes) and analysis of results
» Study of, as permitted by the Privacy Act ,of
tobacco (or alcohol) consumption
» Analysis of influences on sport
» Study of users communication through the analysis
of the texts of the messages and posts
» Study of the influence of friendship on the social
network on school performance
» Study of segregation (32% of the students are
children of immigrants)
2013 Siena Workshop at Rutgers

4. 04/05/2013
» Attributes in the explanation of social behavior
» Availability of longitudinal data
» Possibility to collect dynamic data on multiple
social relationships
» Control effects of segregation
» Text mining for semantic analysis and impact of
content analysis
2013 Siena Workshop at Rutgers

5. In December 2012 we installed at Tito Sarrocchi , an high school of Siena, a
platform Facebook like (based on the Elgg open source software) named MyTito.
The school currently has 1,600 students. All students are registered by default.
After 3 months, active users to the social network are 253.
N
59
49
59
42
38
253
04/05/2013
Class
I
II
III
IV
V
Total
Mean Age
2013 Siena Workshop at Rutgers
%
23%
19%
23%
17%
15%
100%
15,4
Gender
Immigrants
67
9
26,5%
29,0%
Male
186
22
%
Total
73,5%
253
71,0%
31
Female
%

6. 04/05/2013
Sarrocchi representative students periodically organize meetings to explain
to their colleague how MyTyto works. The peaks correspond to those
days. Between February and March there was a slight growth in traffic.
2013 Siena Workshop at Rutgers

7. 04/05/2013
22% of users have only a friend on MyTito Social Network site SNs
2013 Siena Workshop at Rutgers

8. 04/05/2013
Density no loops = 0.02169245
2013 Siena Workshop at Rutgers

9. 04/05/2013
» It is not a complete network (in the original
design we wanted to start with a complete
network in which the friendship decayed if
inactive after a period of time)
» It is a multicentric network (groupings between
classes)
» The network stops with a friendship is not
reciprocated
» It is not a dense network
2013 Siena Workshop at Rutgers

10. 04/05/2013
» Communication barriers between the classes
(despite the class representatives hoped that
the social network could help new friendships)
» No interaction with other social network sites
» Facebook competition (Why do invent the
wheel again?)
» Declared uselessness of tool
2013 Siena Workshop at Rutgers

11. 04/05/2013
2013 Siena Workshop at Rutgers

12. 04/05/2013
We do not observe the phenomenon of
segregation.
» The Average Degree (AD) of the network is
equal to 10.97 against the AD of nodes
represented by the immigrants is 7.04
» Furthermore the AD of the partition of only
immigrants is equal to 2.58
2013 Siena Workshop at Rutgers

13. 04/05/2013
2013 Siena Workshop at Rutgers

14. 04/05/2013
A 3-core analysis confirms the polarization into
classes. Complete triads are mainly within the
classroom
2013 Siena Workshop at Rutgers

15. 04/05/2013
2013 Siena Workshop at Rutgers

16. 04/05/2013
Analyze the influences of communication between
users according to their level of awareness of
communication. This communication lines are
characterized by an increasing intensity of relationship
which can be defined on three levels:
» the first level, friendship, is characterized by a low
cognitive involvement;
» the level of private messages is characterized by an
intermediate level of articulation;
» the interaction on the wall is characterized by a
high level of awareness especially if repeated over
time.
2013 Siena Workshop at Rutgers

17. The objective of the PCA is to determine the relevant
base of reference to represent the data and filter the
noise hoping that this new base filters the noise and
reveals previously invisible structures
A. PCA is a linear transformation of the data:
1.
2.
Minimize the redundancy measured by the covariance
Maximize the information, as measured by the variance.
B. The Principal Components (PC) are new variables
that have the following properties:
04/05/2013
1. Each PC is a linear combination of the original variables
2. The PC are between them orthogonal, or are mutually
uncorrelated, removing the redundant information,
2013 Siena Workshop at Rutgers

18. The PCA provides an alternative explanation of
the observed variability with the advantage of
describing the phenomena by unrelated
dimensions and ordered in terms of their
importance in explanation.
This allows to:
1.
04/05/2013
2.
To interpret the phenomenon through the new meaning assumed
by the main components that have not been discarded
to reduce the number of variables to consider, discarding the latest
main components, which less contribute to observed variability
2013 Siena Workshop at Rutgers

19. 04/05/2013
Identification of three components in which to divide the text of messages where only
one is clearly linked to a set of words related to the installation of the platform
Once identified the components, they should be associated with a lexicon and an
ontology
2013 Siena Workshop at Rutgers

20. 04/05/2013
This field experiment although preliminary, has
promising results. Although in the absence of
further qualitative information, data collected
allow us to remarks:
1. The network is partitioned between classes
(this is not sufficient to confirm Homopily)
2. Absence of segregation
3. Content analysis broadly confirmed when
users are focused on particular topics
2013 Siena Workshop at Rutgers

21. 04/05/2013
» To develop APIs connection between MyTito
SNs and Facebook or other SNs
» To build a network with the texts of messages
and posts. It requires a categorization with
which to divide the network into semantic
clusters
» To overlay network users with the semantic one
2013 Siena Workshop at Rutgers