> “if you change things, it costs you schedule days”. When I worked for Philips as a test hardware design engineer in the old Mullard Radio Valve plant in the

> “if you change things, it costs you schedule days”. When I worked for Philips as a test hardware design engineer in the old Mullard Radio Valve plant in the late 70s and early 80s (a major semiconductor plant despite its name) we were even stricter than that. Every project started with a rough estimate for the total cost, we then spent 10 percent of that on a combination of prototypes and a better estimate of the time and cost and refinement of the requirements. The customer department would then decide whether to proceed. At that point the requirements were frozen. Our department was then committed to the project schedule and price and the customer was committed to the requirements. Any changes would require exactly the same procedure as before: rough estimate, 10 percent preliminary study, better requirements and plan, commitment, development, delivery. Part of the purpose of this was that at the end of the ten percent phase the customer could take his requirements to an external supplier (British Aerospace for instance) and get a quote from them instead and possibly actually give them the job.