Viral Spread Models

Overview

Compartmental models (SIR, SIS, SEIR) model how content/information spreads through populations. Susceptible → Infected → Recovered mirrors unaware → sharing → stopped sharing. Key metric: R0 (basic reproduction number). Solves as ODEs in O(T × N) for T timesteps, N compartments.

When to Use

Trigger conditions:

• Modeling how content spreads through a social network
• Estimating whether a campaign will achieve viral threshold
• Analyzing post-hoc spread dynamics of viral events

When NOT to use:

• When predicting individual user behavior (use influence scoring)
• When measuring engagement metrics (use engagement rate calculator)

Algorithm