Lean Analytics is one of the best business books I have read in a long time. The approach is data-driven: build, measure, learn. Measurement focuses on the most critical performance metrics for each stage of a startup, from initial assessment of concept-market fit (Empathy) through scale-up. Metrics are tightly coupled with the underlying business model and the authors analyze each of the principle web-based models: E-commerce, Software as Service, Free Mobile App, Media Site, User-Generated Content, and Two-Sided Marketplaces. The methods are pragmatic and will be useful Internet start-ups and corporate "intrapreneurs" alike.