deletions | additions       diff --git a/Revenstein_law_of_Migration_in__.md b/Revenstein_law_of_Migration_in__.md  new file mode 100644  index 0000000..c37d0a5  --- /dev/null  +++ b/Revenstein_law_of_Migration_in__.md 
...
Revenstein “law of Migration”: in 1880, Ernst Georg Ravenstein published “The law of migration in the   journal of the Statistical Society, which established the theory of human migration that sill forms the basis   for modern migration theories. It considered the implication of distance and type of migrant. Lee (Push-Pull) model: is a model that explains the decision of migration to based on four factor,   characteristics of Origin, characteristics of Destination, Characteristics, Nature of intervening Obstacles,   and Nature of the people.   Gravity migration model (Karemera, Oguledo, & Davis, 2000) is derived from Newton’s law of gravity. It   measures the degree of interaction between two places. And it is based upon the idea that as the   importance of one or both of the location increases there will also be increase in the movement between   them. This model have been widely used in the empirical analysis of migration due to their relatively good   forecasting performance. But since it is based observations, it is considered that it cannot be confirmed   scientifically.   Spatial interaction model is a common deterministic model used in migration analysis based on Gravity   model. Where the migration between to origin i and destination d is proportional to the product of   populations at origin and destination and inversely proportional to the distance between them.     (Kunz, 1973) created the first universal topology of characterizing migrations and a seminal paper by   (Simini, González, Maritan, & Barabási, 2012) combined the lessons from scale-free networks with   previous migration models to yield a unified model of migration, suggesting that the gravity model   combined with the spatial model can give an accurate model of migration and indicate different ‘threshold   levels’ at which humans are triggered to move. Studying the interaction of two population groups   competing for one pathc of land, (Auger & Poggiale, 1996) found that migration is much faster social   phenomenon that population growth and people would have and a particular choice of density dependent   migrations leads to an aggregated competition model. In an attempt to view migration a lifecycle process,   (Ryan, Dooley, & Benson, 2008) propose a resource-based model for migration, but they specify that the   resources in this case must be understood as those fulfilling the needs of individuals – and they might   change over time so they must be monitored before, during and after migration. Already in (Borjas, 1989)   postulated that migration is an economically driven phenomenon and can be explained purely by the laws   of markets, attributing a net economic loss to the worsening conditions that would trigger the migration   and he also analyzed the impact of migrants on target countries’ economies – applied to Vietnamese   refugees in the US by (Montero, 1979) – while (Boyd, 1989) characterized migration mainly as a social   phenomenon, driven by family ties.   One of the most striking characteristics if the current Syrian refugee crisis is the seemingly dormant state   for 4 years (due to being largely underreported by the mainstream media and people fleeing at   comparably constant rates to today’s values into neighboring countries) and then a sudden intensification   of flows towards Europe in the past year. (Zolberg, 1989) suggested that due to globalization and   economic integration, labor outsourcing, migration will intensify in the next few decades – a prediction   that what spot on even without foreseeing the unpredictable social catastrophes in the Middle East or   Africa (Neumayer, 2005).   With the advent of many international organizations getting well-funded statistics departments, there   was a surge in the need of characterizing data streams. Therefore, many different definitions of a what   constitute of a refugee and what constitute a migrant appeared, oftentimes with the sole purpose of   presenting the refugee numbers in a ‘better light’ (Zetter, 2007).