【正确答案】 1、mathematical modeling    

【答案解析】[详细解答] 文章中谈到“几年前，由于直接统计方法还没有实施，资深人口统计学家巴里·埃德蒙斯顿(Barry Edmonston)在指导美国科学院全国研究会(National Research Council of the American Academy of Sciences)所做移民研究时，他“used sophisticated mathematical modeling techniques to calculate how intermarriage is changing the face of the United States as part of an immigration study he directed for the National Research Council of the American Academy of Sciences．”。