Interaction data are inherently more complex than standard count data – origin and destination. One of the principal purposes of any classification is to simplify complex data to aid understanding.

• Interaction data are inherently more complex than standard count data – origin and destination. One of the principal purposes of any classification is to simplify complex data to aid understanding.

• District level classifications such as those developed by ONS and Vickers et al. have been created without the use of migration/commuting variables.

• Underlying populations in areas may or may not be representative of migrant populations; thus classifying areas separately by their migrants may reveal things not shown in other general purpose classifications.

Notes:

It may be very useful from a policy perspective to know, for example, if an area is particularly prone to receiving relatively high numbers of elderly in-migrants or losing high numbers of skilled workers.