他们的研究起点是一项观察：二战以来（从杜鲁门到奥巴马 ） ， 平均年GDP增长率在民主党执政时期为4.3 % ， 而共和党执政时期为2.5 % 。
Their starting point is the observation that in the post-World War II period (from Harry Truman to Barack Obama), annual GDP growth has averaged 4.3% during Democratic administrations, compared to 2.5% under Republicans.