The Lean Startup: How Today's Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses · chapter 10 · id the-lean-startup-c10-04-for-the-viral-engine-of-growth

“For the viral engine of growth, the key metric is the viral coefficient (k), which must be greater than 1.0 for true viral growth. Even small changes in k have massive compounding effects.”

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Receipts

Andrew Chen -- Viral Coefficient Analysis (2008)FLAGGED: dead link (404)

Chen analyzed viral coefficients extensively in 2008. Very few products achieve k > 1.0 sustainably. Most viral growth is actually sub-viral (k < 1.0) supplemented by paid acquisition.

Goldenberg, Libai & Muller (2001), Network Effects in Markets, Marketing ScienceFLAGGED: DOI not in registry

Network-driven growth models show that sustained k > 1.0 is extremely rare and typically temporary. Most 'viral' products have k between 0.3 and 0.8.

First Round Review -- Growth frameworkssource alive

In practice, almost no product maintains k > 1.0 for more than a few weeks. Facebook, the canonical viral product, grew through a combination of viral + network effects + paid acquisition.

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