Aace 将项目开发周期中的投资估算划分为 5 个等级, 即 1 级至 5 级估算,其中 5 级估算在项目开发初期阶段编制, 精度最低,1 级估算在项目定义基本完成阶段编制,精度最 高。 Founded in 1956, aace is the world's first professional organization in the fields of project management and related cost estimation, schedule planning, cost/schedule control (project.