Vanity metrics wreak havoc because they prey on a weakness of the human mind. - Eric Ries

The growth is all coming from an engine of growth that is working — running efficiently to bring in new customers — not from improvements driven by product development.

Startups are different: too much budget is as harmful as too little — as countless dot-com failures can attest — and startups are extremely sensitive to midcourse budgetary changes.

Should this product be built?” and “Can we build a sustainable business around this set of products and services?” To answer those questions, we need a method for systematically breaking down a business plan into its component parts and testing each part empirically.