Lecture 12 - YouTube

YouTube was founded in…

February 2005, by October 2009 they were breaking 1B daily views

By 2020…

Second largest “search engine” and second most visited website after Google.

YouTube and third-party apps offer…

YouTube insight, statistics and analytics

YouTube Clip: Web Search

Google

YouTube Clip: Refferal

Through email, Twitter and Facebook

YouTube Clip: Subscription

To a YouTube channel

YouTube Clip: Browsing

through the YouTube recommendation page

Co-visitation Count

How often pair of videos watched together by viewers in some timeframe.

Simpler because…

YT does not yse Page-Rank style: tags are unreliable. Also do not use Netflix style: viewing data too variable for short clips

“Viral” typically indicates these three features:

1. High total view count

2. Rapid increase of sufficient duration

3. Short time before rapid increase begins

Popularity depends on…

Intrinsic value and Network effect.

Intrinsic Value

Independent of what others think

Network Effect

Others’ opinions gives you information:

• fallacy of crowds

• information cascade

Value of service/product depends on number of people using it

• Fax machine, Wikipedia

• Positive network effect

Information cascade

People observe actions of others and follow crowd, irrespective of own instincts

Information Cascade Example

Follow an incorrect group answer

Sequential Decision Making

Get private signal, release public actionInfor

Positive Feedback

More likely to follow if more are already. Move in same direction as “error signal” (recall negative feedback)

Fragile

Can disappear / reverse direction if private signals are released

Sequential Decision Making

• Information cascade

• Positive Feedback

• Fragile

• CAN BE WRONG

Triggering a Cascade

Two people in a row must show same public action

Guaranteed Cascade Eventually…

Could be correct or incorrect, but significant chance that it is incorrect

Counter - Intuitive

Cascades block aggregation of independent information.

Cascade will last until a disturbance:

Release of private signals.Brea

king cascade 

Cascade of 1’s: someone shouts 0, next private signal is 0.F

or viralization…

You want your video to undergo cascade.

Information cascade is population-based:

No account for specific social relationships.