The In-migration Field Gini Index is a decomposed version
of the Columns Gini Index
(`migration.gini.col`

) representing "the
contribution of each region's columns to the total index"
() (`migration.gini.total`

):

*G^I_j =
\frac{∑_{i \neq j} ∑_{k \neq j,i} | M_{ij} - M_{kj}
| }{ 2(n-2) ∑_{i \neq j} M_{ij}}*

These Gini indices facilitates the direct comparison of different territories without further standardization.

1 | ```
migration.gini.in(m, corrected = TRUE)
``` |

`m` |
migration matrix |

`corrected` |
Bell et al. (2002) updated the formula
of Plane and Mulligan (1997) to be |

A numeric vector with the range of 0 to 1 where 0 means no spatial focusing and 1 shows maximum focusing.

David A. Plane and Gordon F. Mulligan (1997) Measuring Spatial Focusing in a Migration System.

*Demography***34**, 251–262M. Bell, M. Blake, P. Boyle, O. Duke-Williams, P. Rees, J. Stillwell and G. Hugo (2002) Cross-National Comparison of Internal Migration. Issues and Measures.

*Journal of the Royal Statistical Society. Series A (Statistics in Society)***165**, 435–464

`migration.gini`

`migration.gini.out`

`migration.weighted.gini.in`

1 2 3 4 5 | ```
data(migration.hyp)
migration.gini.in(migration.hyp) # 0.2000000 0.5000000 0.3333333
migration.gini.in(migration.hyp2) # 0.2000000 0.0000000 0.4285714
migration.gini.in(migration.hyp, FALSE) # 0.1000000 0.2500000 0.1666667
migration.gini.in(migration.hyp2, FALSE) # 0.1000000 0.0000000 0.2142857
``` |

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