2 What is a model?a representation of some phenomenon of the real-world made to facilitate an understanding of its workingsa simplification and/or generalization of a complex reality from which the incidental detail has been removedan abstraction – not a reality
3 Types of geographic models MathematicalGraphicTextual
4 What do you need to know about models? The associated geographerThe “parts” of the modelThe “assumptions” of the modelCritiques of the modelApplications of the model
5 Most Critical! A model IS NOT a “plan” to be followed in the future. A model IS a “description” of what happened in the past.A model IS NOT a critique of the present.A model IS a pattern to which we can compare the present in order to see differences.
6 Tobler’s Law of Gravity Waldo Tobler"Everything is related to everything else, but near thing s are more related than distant things.”
7 Gravity Model Uses size of location and distance as factors for travel Size of location takes precedent over distanceThe gravity model can be used to estimate:Traffic FlowsMigration between two areasThe number of people likely to use one central place
8 The GRAVITY MODEL of MIGRATION is a model, derived from Newton's law of gravity. Newton's law states that: "Any two bodies attract one another with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them." The GRAVITY MODEL of MIGRATION is used to predict the degree of interaction between two places
9 When used geographically, the words 'bodies' and 'masses' are replaced by 'locations' and 'importance' respectively,.Importance can be measured in terms of population numbers, gross domestic product, or other appropriate variable.
10 The gravity model of migration is therefore based upon the idea that as the importance of one or both of the location increases, there will also be an increase in movement between them.
11 The farther apart the two locations are, however, the movement between them will be less. This phenomenon is known as distance decay.
12 The simplistic version of the gravity model of migration is as follows: Mij = gravity model prediction of migration between origin i and destination jPi = population of origin State iPj = population of destination State jdij = distance from origin i to destination jMij=Pi*Pjdij2
13 CITY ATLANTA NEW YORK CITY KNOXVILLE AUSTIN LOS ANGELES CHICAGO TULSA POPULATION (2012)ATLANTA443,775NEW YORK CITY8,336,697KNOXVILLE182,200AUSTIN842,592LOS ANGELES3,857,799CHICAGO2,714,856TULSA393,987COMPARE ATLANTA TO EACH OF THE CITIES LISTED
14 How might the calculations of distance you came up with differ from actual travel distances in real life?What other factors might influence people to travel to one city or another (other than distance decay)?How accurately do you believe the gravity model formula predicts actual migratory patterns between places? Explain.
15 Earnest Ravenstein (1885)1) Most migrants only travel short distances to higher populated areas2) Migrants created gaps through the flow towards the higher populated areas filling up space between origin and destination3) Counter-current of migration at destination4) Long distance migrants flock towards world cities or large industrial areas5) The natives of towns are less migratory than those of the rural parts of the country6) Females are more migratory than malesUntil recentlyMen, or couples w/o children, young adult or senior citizens, no dependents
16 Migration Issues Push factors Pull factors Forced Migration Refugees Things that push people to move away from a locationPull factorsThings that draw people to a locationForced MigrationPeople forced to leave a given place permanentlyUsually based on ethnicity, religion, ideology, etc.RefugeesPeople leaving a location for fear of persecution or deathWar-torn nations, religious persecutionCuban refugeesIntervening obstaclesThings that block migration streamsIntervening opportunitiesThings that attract people while in the migration stream
17 Cultural Hearths The center or starting point of a cultural trait Regions can be defined by hearthsExamples?Vatican CityBirth of Blues (Memphis, Tennessee)
19 Assimilation Acculturation The spread of a cultural complex or a cultural trait from one location to anotherThe process of another culture embracing or adding that cultural trait to their cultural complexAssimilationA culture is completely dominated by another cultureForced migrationImperialization