مقایسهٔ روش‌ها

	Survival Analysis of First Migration	Discrete-Time Hazard of Migration
حوزه	Migration Studies	Migration Studies
خانواده	Survival analysis	Survival analysis
سال پیدایش	1993	1982
پدیدآور	Hans-Peter Blossfeld & Götz Rohwer; Clara Mulder	Paul D. Allison
نوع	Continuous-time hazard model of the first migration event	Discrete-time hazard model of migration timing
منبع بنیادین	Blossfeld, H.-P., & Rohwer, G. (2002). Techniques of Event History Modeling: New Approaches to Causal Analysis (2nd ed.). Lawrence Erlbaum. ISBN: 9780805840919	Allison, P. D. (1982). Discrete-Time Methods for the Analysis of Event Histories. Sociological Methodology, 13, 61-98.
نام‌های دیگر	Hazard Model of First Move, Time-to-First-Migration Analysis, Age-at-First-Migration Survival Model, First-Move Event-History Analysis	Person-Period Logit Migration Model, Allison Discrete-Time Event-History Model, Annual-Data Hazard of Moving, Complementary Log-Log Migration Model
مرتبط	3	3
خلاصه	Survival analysis of first migration treats the move out of one's place of origin as a timed event and asks not whether but when a person first migrates. Rather than modeling a binary 'migrated or not' outcome, it follows individuals from the moment they become at risk and models the instantaneous hazard of a first move as a function of age and changing life circumstances. The approach, codified for the social sciences by Blossfeld and Rohwer's event-history framework and applied to migration biographies by Clara Mulder, handles the two features that defeat ordinary regression: censoring, because most people in a sample have not yet migrated when observed, and time-varying covariates, because the things that trigger a move — finishing school, finding a job, forming a union — themselves change over time. The result is an estimate of how the risk of a first move rises and falls across the life course and how it responds to time-dependent conditions. It can be fitted nonparametrically with a Cox model or with a parametric baseline when the shape of age dependence is of interest.	The discrete-time hazard model analyzes the timing of migration when the data arrive in chunks of time — usually person-years — rather than as exact dates. Paul Allison's 1982 formulation showed that an event history measured in discrete periods can be analyzed by a remarkably simple device: expand each person into one record per period they are at risk, mark whether the move happened in that period, and fit an ordinary binary regression (logit or complementary log-log) for the conditional probability of moving. The baseline period enters as a set of terms capturing duration dependence — how the risk of moving rises or falls with time elapsed — and covariates can change from period to period. Because annual migration data are the norm in panels and registers, this person-period approach has become the standard event-history tool in migration research, sitting alongside the continuous-time Cox model and extending naturally to competing destinations and repeat moves. Its great practical virtue is that the entire apparatus reduces to a logistic regression any analyst can run.