Fermi Questions to Estimate Software Development Projects

Experienced professionals are capable of spotting an impossible estimate at a glance. This ability, which some will call "expert knowledge" is acquired over years of practice and observation of what works and does not work. Expert knowledge is mostly tacit and in consequence difficult to pass on. Fermi questions, named after Enrico Fermi - a Nobel Laureate in Physics, seek to produce a quick, rough estimate of a quantity that is either difficult or inconvenient to measure directly or for which we do not have all necessary data to calculate.