Compare contagious diffusion and hierarchical diffusion, including an example for each.

• A. Contagious diffusion spreads through a network of orders or nodes.
• B. Contagious diffusion spreads rapidly through a population; hierarchical diffusion spreads through a network of orders or nodes (e.g., celebrity fashion trends; adoption in major cities).
• C. Contagious diffusion occurs only for diseases; hierarchical only for fashion.
• D. They are the same.

Answer: (B)

Contagious diffusion is about rapid spread through direct contact across a population. It doesn’t depend on a hierarchy of places or people; the idea is that people influence those around them in their immediate social networks, so a disease, rumor, or viral trend can spread quickly to many individuals in a short time. An everyday example is a contagious disease moving from person to person, or a meme that goes viral as people share it with friends and family.

Hierarchical diffusion, on the other hand, moves through a network of ordered places or people, starting with influential hubs and then passing down to others. It often begins in major cities, with celebrities, brands, or media outlets picking up a trend first, and then the trend spreading to less connected areas as those hubs influence others. An example is a fashion trend that first appears in fashion capitals or among celebrities and then spreads to smaller cities and eventually to the broader public.

The statement that contagious diffusion spreads rapidly through a population and hierarchical diffusion spreads through a network of orders or nodes captures these distinct patterns and their typical examples.