**<u>Table 6. Database versions</u>**

|**Version**|**Number**<br>**of**<br>**migrants**<br>**treated**|**Information contained**|**Main countries whose status is**<br>**changed from previous version**|
|---|---|---|---|
|1|FB 108.5m<br>Nat 55.3m|Raw data collected including older primary<br>sources where later information<br>unavailable.<br>Meaningless "unknown" totals omitted.<br>Those countries where totals reported prior<br>to break-up redistributed according to<br>bilateral migration stocks post break-up.<br>Aggregated in dependences.<br>Entered zeros where applicable.||
|2|FB 111.0m<br>Nat 56.2|Separated jointly reported nations, and<br>those prior to break-up where no post<br>break-up migration data available,<br>according to populationshares.|**Disaggregated according to subsequent**<br>**migration stats**:<br>Germany, Italy, Canada, Denmark, Sweden,<br>Finland|
|3|FB 111.0m<br>Nat 57.6|Removed ethnic nationalities with little or<br>no correlation to states or regions.<br>Added additional DFID figures on the<br>number of Indians residing in Middle<br>Eastern Economies.<br>Removed ambiguous and "ignored"<br>categories as these most likely account for<br>domestic population and not migrants.<br>Removed those recorded with dual<br>nationality.|**Removed meaningless ethnicities:**<br>Bulgaria, Romania, Slovakia, Croatia, Belarus,<br>Kazakhstan, Kyrgyzstan, Moldova, Turkmenistan,<br>Tajikistan, Uzbekistan<br>**Removed unknown and ignored figures:**<br>Argentina, Netherlands, Sweden, Thailand,<br>Greece, Bulgaria, Hungary<br>**Added DFID figures:**<br>Qatar, Oman, Bahrain, Kuwait<br>**Removed dual nationality:**<br>Liechtenstein|
|4a|FB = Total<br>= 175.7m|Entered United Nations data for country of<br>birth totals where data missing.<br>Used entropy measure to compare<br>nationality and country of birth shares.<br>Having confirmed that the series were<br>highly correlated, used the additional<br>information content in the nationality matrix<br>to supplement the foreign-born matrix with<br>additionalcoefficients of interest.|**Countries included where no data previously:**<br>China, Indonesia, Democratic People's Republic<br>of Korea, Morocco, Algeria, Yemen<br>**Countries that had nationality data used to**<br>**supplement FB Matrix:**<br>Japan, Philippines, Thailand, Vietnam, Italy,<br>Mozambique|
|4b||Disaggregated remainder categories<br>based on countries’ propensity to send<br>migrants abroad.||
|4c||Used shares based on countries’<br>propensity to send migrants abroad to fill<br>all remaining bilateral coefficients.<br>Scaled data to UnitedNations (2004)||

# **_5._ What the Data Show**<sup>**_20_**</sup>

The principal purpose of this paper is to introduce a dataset that we believe will be useful for other researchers. We intend to use it for several purposes, such as updating the Walmsley and Winters (2005) analysis of the economic benefits of migration, in which the lack of bilateral migration data severely hampered the estimation of the distribution of those benefits. The aim of this section is not to embark upon such a detailed analysis but briefly to illustrate the patterns that the bilateral data display both for their intrinsic interest and to allow readers to judge whether the whole enterprise is plausible. Most of the value of the bilateral data lies in their country detail, but that is far too great for us to

> 20 This summary refers to the current version of the dataset. Ratha’s (2006) results and data (which focus on the South-South dimension) differ a little: his are scaled up to 2005, contain 14 fewer countries but 15 million more migrants, have treated "other" and residual categories differently, and have combined foreign-born and foreign nationality differently.

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