One of the main efforts devoted by the authors is the design and collection of information but the first concern is the data. The authors claim their sample were designed to get information for individuals with high ability rather than based on occupations in order to avoid self-selection. However, when they collected the information there is some bias because the type of students they chose. For instance, in the case of NZ they collected information of participants on the chemistry and math Olympians – they got the highest rates of response – so when doing the probit model of the determinants of migrating having studied three science subjects a is not surprised to that variable to appear as a positive perfect predictor for migration (Gibson and David McKenzie, 2011a:26).
Literature on design and collection on of data has also shown in the households surveys people lie regarding their income under-reporting or over-reporting (Tourangeau and Smith, 1996). So when collecting information about determinants of migration is possible that people were tempted to lie not only about their income but also on other factors related to their labour market or migration conditions depending on the cohort of age and their status.
Findings and “Other Determinants of Migration”
The literature suggests negative implications of brain drain since a common concern is the amount that developing countries lose from investing in their citizens' education. However, one implication of Gibson and McKenzie’s is that apparently in the countries of study brain drain is not a problem since skilled human movement there has high rates of return and therefore this region does not necessarily cause country great losses. Then some major reasons for the outward movement in the countries chosen could reflect the desire to gain work experience or taking a work overseas to defray living and travelling expenses while staying abroad (Birrell et al., 2001).
There is a large literature which looks at what determines the share of a country‘s migrants who are highly skilled. In the macro determinants, the research of Gibson and McKenzie lacks the findings of Borjas (1987), who noted the importance of inequality in the sending country relative to destination countries predicting negative selection, in other words, migrants are more likely to be low-skilled when inequality in the home country is higher than that abroad. Nevertheless Gibson and McKenzie focused on top student and there is evidence that emigration levels are almost universally higher among tertiary-educated individuals, it could be interesting to introduce those elements in their probit model of migration.
Additionally, it is important to mention that an assessment of those Pacific countries brain drain phenomena cannot be fully understood with macroeconomic determinants omitted in the models such path dependence patterns (colonial links, language), networks and geographical distance between the countries.
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