<P> In 1962, Everett Rogers, a professor of rural sociology, published his seminal work: Diffusion of Innovations . Rogers synthesized research from over 508 diffusion studies across the fields that initially influenced the theory: anthropology, early sociology, rural sociology, education, industrial sociology and medical sociology . Using his synthesis, Rogers produced a theory of the adoption of innovations among individuals and organizations . Diffusion of Innovations and Rogers' later books are among the most often cited in diffusion research . His methodologies are closely followed in recent diffusion research, even as the field has expanded into, and been influenced by, other methodological disciplines such as social network analysis and communication . </P> <P> The key elements in diffusion research are: </P> <Table> <Tr> <Th> Element </Th> <Th> Definition </Th> </Tr> <Tr> <Td> Innovation </Td> <Td> Innovation are a broad category, relative to the current knowledge of the analyzed unit . Any idea, practice, or object that is perceived as new by an individual or other unit of adoption could be considered an innovation available for study . </Td> </Tr> <Tr> <Td> Adopters </Td> <Td> Adopters are the minimal unit of analysis . In most studies, adopters are individuals, but can also be organizations (businesses, schools, hospitals, etc .), clusters within social networks, or countries . </Td> </Tr> <Tr> <Td> Communication channels </Td> <Td> Diffusion, by definition, takes place among people or organizations . Communication channels allow the transfer of information from one unit to the other . Communication patterns or capabilities must be established between parties as a minimum for diffusion to occur . </Td> </Tr> <Tr> <Td> Time </Td> <Td> The passage of time is necessary for innovations to be adopted; they are rarely adopted instantaneously . In fact, in the Ryan and Gross (1943) study on hybrid corn adoption, adoption occurred over more than ten years, and most farmers only dedicated a fraction on their fields to the new corn in the first years after adoption . </Td> </Tr> <Tr> <Td> Social system </Td> <Td> The social system is the combination of external influences (mass media, surfactants, organizational or governmental mandates) and internal influences (strong and weak social relationships, distance from opinion leaders). There are many roles in a social system, and their combination represents the total influences on a potential adopter . </Td> </Tr> </Table> <Tr> <Th> Element </Th> <Th> Definition </Th> </Tr>

Adopter categories based on relative time of adoption of innovations
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