1. Tenth Link: Viruses and Fads
Gaetan Dugas and the spread of AIDS. He was known as Patient Zero.
He is an example of the power of HUBS
Mike Collins created a cartoon about the 200 Florida ballot and he sent it to 30 of his friends.
The cartoon circled the globe and a business was born overnight.

2. The Spread of Viruses and Fads
Depends heavily on first adopters, also known as innovators.
Ipod
Apple Newton
Palm Pilots
Hybrid Corn Seed
Early Adopters
Early Majority
Late Majority
Lagards

4. How do Social Ties effect Behavior
1954 Elihu Katz circulated a proposal to study the effects of social ties on behavior.
Fellow Columbia Alumni, was the director of Market Research at Pfizer
He offered Katz and his partners 40K dollars to track the spread of Tetracycline.

5. Katz, Coleman, and Menzel Study

6. Results
A few of the doctors were named by a large fraction of their colleagues as playing an important role in day to day decisions. These are known as the HUBS
The doctors who were named as friends were 3x’s more likely to adopt the new drug.
Prescriptions were followed using the local pharmacies records.
The early adopters and early majority had numerous social links.
The trend would then spread to doctors who were not as connected.

7. What is a HUB Hubs are often referred to as
Opinion Leaders
Power Users
Influencers
They are individuals who communicate with more people about a certain product than the average person.
They are the first to notice and use the experience of the Innovators
If the hubs resist a product a wall will be formed and the product will likely fail.

8. Apple Newton Fails, but the a market is born!
The First Mover does not always have the advantage.
A number of poor reviews about the Newtons hand writing recognition application.
Extremely poor battery life
Why did Newton Fail? (Advertising is not a sufficient Argument)

10. Threshold Model We all differ in our willingness to accept innovation.
Diffusion Models assign a threshold to each individual, quantifying the likelihood that he or she will adopt a given innovation.
All products have a Spreading Rate.(From introduction to purchase)
Crititical Threshold- A quantity determined by the properties of the network in which the innovation spreads.
If the spreading rate is lower than the critical threshold, the product will die out. If it is higher, then eventually, every user who can, will adopt the innovation.
Critical Threshold is part of every diffusion theory today.