nationals. The fourth version covers only the foreign-born. Version 1 contains all the raw data collected with a few adjustments. In the sources drawn upon in this paper it is common for migrants that cannot be assigned to a specific country of birth/nationality to be recorded in remainder categories that typically have the prefix "Other". In version 1, there is no attempt to reassign these migrants and the "Other" category, which often contributes significantly to the overall total, is simply reported below the matrix in the relevant (host nation) column. In a few cases, large "unknown" categories were recorded in the original data, for example the German data collected from the OECD. These "unknowns" were completely removed from the matrices since it is unclear whether they actually refer to migrants, and will often contain members of the domestic population, since domestic populations are normally far larger than foreign populations. Where countries used country coding referring to the USSR, Czechoslovakia or Yugoslavia, and where bilateral information on migrants’ destination post break-up was available, these aggregated totals were distributed on the same basis, implicitly assuming therefore that migration proportions were the same after break-up.<sup>15</sup> Zeros were entered where it could be inferred from the data that no migrants were assigned to a specific country. Dependencies and re-coded countries were also aggregated up into one of the 226 countries and territories included in the database.

In version 2 of the matrices, composite or regional origins for which no country-specific migration data were available (including break-up countries) are disaggregated according to their shares in total population.<sup>16</sup> Though a rudimentary method of estimation, as migrants are more likely to come from countries in close proximity at the regional level (Harrison, Britton and Swanson 2003), this method was deemed a reasonable exercise. As an example, the 1996 New Caledonia census recorded one category as "Melanesia", which included 86,788 unassigned migrants from Fiji, Solomon Islands and Papua New Guinea (PNG). Vanuatu was not included under "Melanesia" as it constituted a separate category in the census. Table 3 demonstrates how these migrants for New Caledonia were distributed across these countries in direct proportion to their populations. Table 4 outlines regions and their constituent countries.<sup>17</sup>

**<u>Table 3. New Caledonia migrant split based on population shares for Melanesia</u>**

<!-- Start of picture text --> % total<br>Melanesian<br>population<br><!-- End of picture text -->

|**Country**|**Population (1996)**|**% total**<br>**Melanesian**<br>**population **|**Number migrants**<br>**assigned**|
|---|---|---|---|
|Fiji|786,603|13.5|11,710|
|Solomon Islands|410,641|7.0|6,113|
|PNG|4,456,781|76.4|66,346|
|**Total**|5,829,952|100|86,788|

> 15 Both of these assumptions are open to challenge but, given the data availability, it is difficult to think of better alternatives than just making them and owning up.

> 16 These were, by and large, small remainder categories that overlapped with larger "other" categories, those disaggregated in versions 4a-4c.

> 17 Jointly reported countries, those recorded by name, for example "Botswana and Swaziland" are omitted from table 5.

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