Criterion for classifying adopter categories (Everett Rogers, 1962):

• In diffusion research, Innovativeness is defined as the degree to which an individual or other unit of adoption is relatively earlier in adopting new ideas than other members of a social system.
• Innovativeness is the sole continuum/basis utilized by Rogers to partition populations into the 5 standard adopter categories along a normal bell-shaped distribution.
• Relative advantage and compatibility are perceived attributes of innovations, while rate of adoption is a system-level measure.

Five perceived attributes of innovations (Rogers):

• Four attributes are positively correlated with the rate of adoption:
• Relative Advantage ($+$)
• Compatibility ($+$)
• Trialability ($+$)
• Observability ($+$)
• Only Complexity (the degree to which an innovation is perceived as relatively difficult to understand and use) is negatively related to its rate of adoption.
• The greater the complexity, the slower the adoption rate.

Y.P. Singh and Udai Pareek's Indian adoption model (1965):

• Singh established that in farming communities, perceived Need precedes awareness of specific technologies:
• Need (B)
• Awareness and Interest (A)
• Deliberation and Trial (D)
• Evaluation (E)
• Adoption (C)
• Unlike Western models that start with Awareness, Singh recognized felt Need as the initial impetus for information seeking.
  Sequence: (B) $\rightarrow$ (A) $\rightarrow$ (D) $\rightarrow$ (E) $\rightarrow$ (C).