Forecasting time to move an item through dev cycle is best done this way, using historical data. But if you want to know how long it will take to build "new sy

Forecasting time to move an item through dev cycle is best done this way, using historical data. But if you want to know how long it will take to build "new system we have never done before" then, we are back to the estimation because i have to build a model of what the system will be - and although Incan think Inammaccurate I won't be ... In then end forecasts and estimations are just able to answer two things - when wont it be ready (ie it's definitely going to take longer than two months) and have you thought of all the foreseeable risks?