Business decisions are made by the customer, not by development. Development is not able to resolve business disputes -- hence the customer must speak with one voice.
To quote ExtremeProgrammingInstalled: Whether they are one or many people, the XP customer always speaks with one voice. The determination of what will have business value, and the order of building that value, rests solely with the customer.PlanningExtremeProgramming (p. 81) mentions spatial reasoning as a way to get one voice from a committee of customers (proposed by James Goebel). Interface Systems has a ProductManager responsible for planning long-term releases, a ConsultingTeam? that generates short-term requirements, and a CustomerServiceManager? responsible for qualifying product bugs and scheduling repairs.
In order to accommodate these multiple voices, the size of the StoryCard represents the effort needed. One iteration corresponds to a fixed "playing board", and the committee plays around with the cards until the playing board is filled.
Neat!! --ArieVanDeursenCategoryCustomer | See also WorkshopOnCustomerInvolvement.