In the early stages of a tech startup's life, it's hard to decipher the meaningful metrics from the distractions. How do you know if your product is working? Is it the number of new signups? Average amount of time spent on the site? Revenue, even if you don't have a revenue model yet? In Scaling Lean, serial entrepreneur and author of the startup cult classic Running Lean Ash Maurya offers a tactical handbook for measuring and scaling a tech startup with maximum efficiency and efficacy.