1. Diffusions of Innovations by Everett M. RogersChapter 8 Summary Opinion Leadership, Communication Networks and Critical Mass

2. Homophily vs. Heterophily

Homophilyis the degree to which a pair of individuals who communicate aresimilar

• Provides effective communication amongst groups

• Found in most interpersonal diffusion networks

• Can act as an invisible barrier to the flow of innovation within a system

Heterophilyis the degree to which pairs of individuals who interact aredifferent

• The diffusion process ultimately occurs through communication links that are somewhat heterophilous

3. Opinion Leadership Table 8-1. Advantages and Limitations of Four Methods of Measuring Opinion Leadership and Diffusion Networks -Obtrusive -High validity None Identify and record communication network links as they occur. Observation -dependent upon the accuracy with which respondents can identify and report their self images -measures the individuals perceptions of her/his opinion leadership Are you a leader in this system? Ask each respondent a series of questions to determine the degree to which he/she perceives himself/herself to be an opinion leader. Self-designating method -informants must be familiar with the system -cost saving method -time-saving method Who are leaders in this system? Ask subjectively selected key informants in a system to designate opinion leaders Informants ratings -complex -requires a large number of respondents -easy to administer-adaptable to different types of settings and issues-highest validly Who is your leader? Ask system members to whom they go for advice and information about an idea Sociometric method Limitations Advantages Questions Description Measurement 4. Characteristics of Opinion Leaders

External Communication

• Opinion leaders have greater exposure to mass media

• Opinion leaders are more cosmopolite

• Opinion leaders have greater contact with change agents

Accessibility

• Opinion leaders have greater social participation

Socioeconomic Status

• Opinion leaders have higher socioeconomic status

Innovativeness

• Opinion leaders are more innovative than their followers, but are not necessarily the innovators

5. Critical Mass

Critical mass occurs at the point at which enough individual in a system have adopted an innovation so that the innovations further rate of adoption becomes self-sustaining

critical mass http://www.cirpa-acpri.ca/images/toronto97/97_proceedings/geoghegan.html 6. Important Terms

Communication networkconsists of interconnected individuals who are linked by patterned flows of information.

Communication structureis the differentiated elements that can be recognized in the patterned communication flows in a system.

Communication network analysisis a method of research for identifying the communication structure in a system, in which network data about communication flows are analyzed by using interpersonal communication relationships as the units of analysis.

Social distanceis the degree to which an individual perceives a lack of intimacy with individuals who differ in socioeconomic status, ethnicity and other variables.

7. Important Terms (continued)

Communication proximityis the degree to which two linked individuals in a network have personal communication networks that overlap.

Personal communication networkconsists of the individuals who are linked by patterned communication flow to a given individual.

Interlocking personal networksare personal networks that consist of a set of individuals, all of whom interact with one another.

Radial personal networkconsists of a set of individuals who are linked to a focal individual but do not interact with one another.

The Strength-of-Weak-Ties Theorystates that the information-exchange potential of communication network links is negatively related to their degree of communication proximity and homophily.

8. Generalizations

Interpersonal diffusion networks are mostly homophilous.

When interpersonal diffusion networks are heterophilous, followers seek opinion leader of higher socioeconomic status, with more formal education, with a greater degree of mass media exposure, who are more cosmopolite, have a greater contact with change agents, and are more innovative.

Opinion leaders have greater exposure

Individuals tend to be linked to others who are close to them in physical distance and who are relatively homophilous in social characteristics.

An individual is more likely to adopt an innovation if more of the other individuals in her or her personal network have adopted previously.