Social Media Mining: An Introduction

P1: Trim: 6.125in×9.25in Top: 0.5in Gutter: 0.75in
CUUS2079-08 CUUS2079-Zafarani 978 1 107 01885 3 January 13, 2014 17:22

226 Influence and Homophily

and so, depending on the context, the observation-based measuring of influ-

ence changes. We next describe three different settings and how influence

can be measured in each.

1. When an individual is the role model. This happens in the case of
   individuals in the fashion industry, teachers, and celebrities. In this
   case,the size of the audience that has been influenceddue to that
   fashion, charisma, or the like could act as an accurate measure. A
   local grade-school teacher has a tremendous influence over a class
   of students, whereas Gandhi influenced millions.


2. When an individual spreads information. This scenario is more
   likely when a piece of information, an epidemic, or a product is
   being spread in a network. In this case,the size of the cascade–
   that is, the number of hops the information traveled – orthe popu-
   lation affected, or therate at which population gets influencedis
   considered a measure.


3. When an individual increases value.As in the case of diffusion of
   innovations (see Chapter 7), often when individuals perform actions
   such as buying a product, they increase the value of the product for
   other individuals. For example, the first individual who bought a fax
   machine had no one to send faxes to. The second individual who
   bought a fax machine increased its value for the first individual. So,
   theincrease (or rate of increase) in the value of an item or action
   (such as buying a product) is often used as a measure.

Case Studies for Measuring Influence in Social Media

This section provides examples of measuring influence in the blogosphere

and on the micrologging site Twitter. These techniques can be adapted to

other social media sites, as well.

Measuring Social Influence in the Blogosphere

The goal of measuring influence in the blogosphere is to identify influen-

tial bloggers. Due to the limited time that individuals have, following the

influentials is often necessary for fast access to interesting news. One com-

mon measure for quantifying the influence of bloggers is to use in-degree

centrality: the number of (in-)links that point to the blog. However, because

of the sparsity of in-links, more detailed analysis is required to measure

influence in the blogosphere.