Studies have often found that recent immigrants have better mental health than natives, whereas established immigrants have no such advantage. This could be interpreted as evidence for immigrants' mental health deteriorating with residence duration—the “unhealthy assimilation hypothesis.” However, the methods used in the literature are unfit to assess whether the mental health differences between recent and established immigrants are due to individual‐level deterioration in mental health, compositional differences between immigration cohorts, or selective remigration. This is because previous studies mostly rely on cross‐sectional data, incur in overcontrol bias, and/or fail to disentangle variation with time since arrival from variation with age or between cohorts. In this article, I propose a novel analytical strategy to test the unhealthy assimilation hypothesis. Using fixed‐ and random‐effect regressions stratified by immigrants' age at arrival and data from waves 1–11 of the UK household longitudinal study, I find no evidence that immigrants' mental health deteriorates with time since arrival: immigrants' mental health trajectories are in line with natives' trajectories with age, and the cross‐sectional finding of more established immigrants having worse mental health is driven by differences between individuals who migrated at different times.

中文翻译：

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不健康的同化或成分差异？解开移民心理健康轨迹与居住期限的关系


研究经常发现，新移民比本地人有更好的心理健康状况，而老移民则没有这样的优势。这可以被解释为移民心理健康随着居住时间而恶化的证据——“不健康同化假说”。然而，文献中使用的方法不适合评估新移民和已定居移民之间的心理健康差异是否是由于个人心理健康状况恶化、移民群体之间的构成差异或选择性再移民造成的。这是因为以前的研究大多依赖于横截面数据，会产生过度控制偏差，和/或未能从随年龄或群体间的变化中理清自到达以来随时间的变化。在本文中，我提出了一种新颖的分析策略来检验不健康的同化假设。使用按移民抵达时年龄分层的固定效应和随机效应回归以及英国家庭纵向研究第 1-11 波的数据，我发现没有证据表明移民的心理健康状况随着抵达后的时间而恶化：移民的心理健康轨迹是与当地人随年龄增长的轨迹一致，横断面发现，更成熟的移民心理健康状况更差，这是由不同时间移民的个人之间的差异所驱动的。