Intervening Obstacles Analysis
Also known as: Migration Barriers Analysis, Obstacle Selectivity Analysis, Lee Intervening Obstacles Framework, Migration Friction Analysis
Intervening obstacles analysis isolates and studies the third term in Everett Lee's 1966 theory of migration: the set of barriers that stand between an area of origin and an area of destination and that must be surmounted before any move, however attractive, can take place. Lee distinguished these obstacles — distance, the cost of transport, legal restrictions, borders, and physical frontiers — from the push and pull factors of the places themselves, arguing that they impose a threshold the net attraction must clear. Crucially, obstacles do more than reduce volume: because the ability and willingness to overcome a given barrier vary across individuals, obstacles act as a filter that selects who migrates, shaping the composition of the flow as well as its size. Massey and colleagues' 1993 appraisal situated this barrier logic within migration theory and connected it to policy levers such as border enforcement and visa regimes that deliberately raise obstacles. The analysis proceeds by enumerating and weighting the relevant obstacles, modeling the threshold they create, and assessing the resulting selectivity. It has become especially salient as states use legal and physical barriers to manage international migration.
Key highlights
- Isolates barriers as a distinct determinant, preventing them from being silently absorbed into a generic distance variable.
- Explains both the volume and, through selectivity, the composition of migration flows within one coherent threshold logic.
- Directly maps onto policy levers — enforcement, visas, quotas, transport cost — making it well suited to evaluating migration interventions.
- Accounts for discontinuous surges and collapses in flows when a barrier rises or falls while push-pull conditions are unchanged.
Intuition
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How it works
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When to use it
Use intervening obstacles analysis when the central question concerns the barriers between origin and destination — their height, their effect on flow volume, and especially their effect on who migrates — rather than the attractiveness of the places themselves. It is the natural tool for evaluating migration policy levers such as border enforcement, visa and quota regimes, transport costs, and physical barriers, and for explaining why flows surge or collapse when a barrier changes while underlying push-pull conditions are stable. The analysis is most informative when obstacle severity can be measured and when origin population composition is known well enough to assess selectivity. It is less suitable when obstacles are minor or roughly constant across the units compared, when the binding constraint is the attractiveness differential rather than the friction (better handled by push-pull or gravity approaches), or when the relevant resistance is foregone alternatives along the route rather than barriers, which the intervening-opportunities model addresses. It pairs naturally with push-pull factor analysis, supplying the obstacle term that framework names but rarely measures.
Strengths & limitations
- Isolates barriers as a distinct determinant, preventing them from being silently absorbed into a generic distance variable.
- Explains both the volume and, through selectivity, the composition of migration flows within one coherent threshold logic.
- Directly maps onto policy levers — enforcement, visas, quotas, transport cost — making it well suited to evaluating migration interventions.
- Accounts for discontinuous surges and collapses in flows when a barrier rises or falls while push-pull conditions are unchanged.
- Obstacle severity is hard to measure and aggregate, especially for legal and informal barriers whose stringency resists quantification.
- Separating the obstacle effect from the attractiveness differential requires exogenous variation in barriers that observational data rarely provide.
- Selectivity analysis demands data on the origin population composition, which is frequently unavailable for the non-migrants left behind.
- Massey and colleagues note the framework describes barriers without a behavioral model of how individuals trade them off against other determinants.
Common pitfalls
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Applications
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Frequently asked
How does this differ from the intervening-opportunities model?
Both invoke what lies between origin and destination, but they mean different things. The intervening-opportunities model treats what is in between as competing chances to stop — opportunities that absorb migrants before they reach a far destination — so distance matters only through accumulated alternatives. Lee's intervening-obstacles analysis treats what is in between as resistance — cost, law, borders, distance as friction — that must be overcome regardless of opportunities elsewhere. One is about diverted demand, the other about a barrier to be cleared. They are complementary: a corridor can have both abundant intervening opportunities and high intervening obstacles, and a full account may need both terms.
Why do obstacles affect who migrates, not just how many?
Because the resources needed to overcome a barrier are unevenly distributed. Money buys passage and legal help, education and connections ease border-crossing and document acquisition, and risk tolerance matters when enforcement is dangerous. When an obstacle rises, it screens out those least able to bear its cost first, so the surviving flow is wealthier, better-connected, and more selected on the relevant traits. This is the mechanism behind Lee's selectivity hypotheses: raising a barrier does not shrink a flow uniformly but reshapes its composition, which is why obstacle analysis is as much about the makeup of migrants as about their number.
Can raising barriers backfire on the policymaker's goal?
Often, because obstacles change behavior in ways beyond simple deterrence. Higher barriers can convert circular movement into permanent settlement, since migrants who fear they cannot re-enter choose to stay rather than risk repeated crossings; they can divert flows to more dangerous routes; and they can select for migrants with the resources to evade enforcement. Obstacle analysis makes these composition and behavioral responses visible by modeling barriers as a selective threshold rather than a uniform tax, which is why it is valuable for anticipating the unintended consequences of restrictive policy rather than only its headline deterrent effect.
Sources
- 1.Lee, E. S. (1966). A Theory of Migration. Demography, 3(1), 47-57.
- 2.Massey, D. S., Arango, J., Hugo, G., Kouaouci, A., Pellegrino, A., & Taylor, J. E. (1993). Theories of International Migration: A Review and Appraisal. Population and Development Review, 19(3), 431-466.
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Cite this page
ScholarGate. (2026, June 23). Intervening Obstacles Analysis. ScholarGate. https://scholargate.app/migration-studies/intervening-obstacles-analysis