人口地理学的基本要点 Basics of population Geography 人口公式: Demographic Equation PopN=PopP+(B-D)+(I-O) PopN=current population PopP=known past population (B-D)=natural increase for time period between PopN and PopP (I-O)-net migration for time period between PopN and PopP人口地理学的基本要点 Basics of Population Geography 人口公式：Demographic Equation PopN=PopP+(B-D)+(I-O) PopN=current population PopP=known past population (B-D)=natural increase for time period between PopN and PopP (I-O)=net migration for time period between PopN and PopP