مقایسهٔ روش‌ها

	Multiregional Migration Projection	Internal Migration Intensity Index
حوزه	Migration Studies	Migration Studies
خانواده	Regression model	Process / pipeline
سال پیدایش	1975	2002
پدیدآور	Andrei Rogers; Frans Willekens	Martin Bell and colleagues (IMAGE programme)
نوع	Matrix cohort-component projection model for multiple interacting regions	Descriptive index of overall internal-migration propensity
منبع بنیادین	Rogers, A. (1975). Introduction to Multiregional Mathematical Demography. John Wiley & Sons, New York. ISBN: 9780471729945	Bell, M., Blake, M., Boyle, P., Duke-Williams, O., Rees, P., Stillwell, J., & Hugo, G. (2002). Cross-national comparison of internal migration: issues and measures. Journal of the Royal Statistical Society: Series A, 165(3), 435-464.
نام‌های دیگر	Multiregional Cohort-Component Projection, Multistate Population Projection, Spatial Population Projection, Rogers Multiregional Projection	Crude Migration Intensity, Aggregate Crude Migration Intensity, CMI / ACMI, Migration Intensity Measure
مرتبط	3	3
خلاصه	Multiregional migration projection extends the classic cohort-component method from a single closed population to a system of several regions that exchange migrants. Developed principally by Andrei Rogers in his 1975 Introduction to Multiregional Mathematical Demography, it replaces the ordinary Leslie matrix with a generalized growth matrix whose blocks carry not only survival and fertility within each region but also the age-specific probabilities of moving from every region to every other. Advancing a stacked population vector — population by age for each region — through repeated multiplication by this matrix projects all regions simultaneously and consistently, so that an out-migrant from one region becomes an in-migrant somewhere else and the system stays closed. The same matrix yields multistate life-table quantities such as expected lifetime spent in each region and the long-run stable spatial distribution of the population. Because the method demands smooth age-specific migration inputs, it is usually paired with Rogers-Castro model schedules, and the comparative findings of Rogers and Willekens's 1986 Migration and Settlement project established it as the standard apparatus of formal spatial demography.	The internal migration intensity index measures how much migration occurs within a country — the overall propensity of people to change their place of usual residence — independently of where they move or what the net redistribution is. Its simplest form, the Crude Migration Intensity (CMI), is just the number of internal migrants over an interval divided by the population at risk, expressed per hundred or per thousand. Martin Bell and colleagues, in their 2002 Journal of the Royal Statistical Society paper and the later IMAGE programme, showed that this apparently simple measure is treacherous to compare across countries because it depends heavily on how the territory is carved into zones: the more, smaller regions you define, the more boundary-crossing 'migrants' you count. They therefore developed the Aggregate Crude Migration Intensity (ACMI), a scale-standardized intensity that corrects for this modifiable areal unit problem, and embedded it in a four-part framework — intensity, impact, pattern, and distance — that separates the overall amount of migration from its net effect, its spatial structure, and its typical range. Grounded in the measurement conventions of the United Nations migration manuals, the index gives demographers a defensible, internationally comparable answer to the deceptively hard question 'how migratory is this population?'