Data and Measures
The data were composed of seventy first-year undergraduates (twelve males and fifty-eight females; mean age = 18.4 years) of the same educational department at a university in central Japan. All participants had their own mobile phone.
Social Network Questions
In this study, four types of friendship networks were classified according to intimacy (superficial, self-disclosing) and communication media (face-to-face, text messages). Participants were asked about their communication patterns over the past 2 weeks. They were asked to choose up to five of their classmates with whom they had (1) greeted face-to- face (“face-to-face superficial networks”), (2) disclosed personal matters face-to-face (“face-to-face self-disclosing networks”), (3) casually greeted via mobile phone text messages (“text message-mediated superficial networks”), and (4) disclosed personal matters via mobile phone text messages (“text message-mediated self-disclosing networks”). In this chapter, we examine the questionnaire data from the third (the beginning of the first semester) and forty-first (the end of the second semester) weeks of their academic year after matriculation to study the changes in social network structure across the academic year. The response rate of this longitudinal survey was 100% in both periods.