The Royal Statistical Society and its Statistics User Forum made a joint submission.
 
Download the full response (pdf format, 70kb)

Summary 
The RSS and SUF recognise the importance of Migration Statistics to inform the policy issues surrounding migration, understand the complexity of trying to measure migration into and within the United Kingdom, and appreciate the efforts made in recent years to improve such statistics. In the context of this, we suggest the following:

• There is a good story to tell in the development of migration statistics - enormous improvements have been made in the quality and quantity of the statistics over recent years.  We are also pleased with the degree of user engagement, and many of the recent improvements have been implemented in response to user demand.
• Despite these recent improvements migration statistics are still not fully adequate for the task of producing robust population estimates or understanding patterns of migration. 
• We are concerned about the capacity to improve migration statistics in an environment where government funding of statistics is being reduced. The potential for further improvements is also limited whilst we rely upon a relatively small sample of migrants from the International Passenger Survey.
• There is an issue with the quality and quantity of migration data at a local level, which has a significant impact upon population estimates in areas with high population turnover.  It also inhibits the public understanding of migration.
• We still rely upon the Census for detailed statistics about migration and migrant characteristics, and to evaluate other estimates of migration. During a period of large migration, such as between the last two Censuses (2001 and 2011), waiting ten years for reliable estimates is not sufficient.
• The level of uncertainty in migration estimates is not fully appreciated or reported, and more needs to be done in this regard.
• Estimates of emigration from the UK are known to be hardest to produce. The potential for use of other countries’ immigration data should be considered to validate the UK estimates. Furthermore, the Office for National Statistics could proactively encourage cooperation between member states of international organisations such as the European Union, OECD and UN to work together on this issue.
• Data from e-Borders should be used to supplement the International Passenger Survey, but will not be able to provide the same level of detail.  A step change in migration statistics would require the development of a population register. This should be considered seriously, particularly if alternatives to a Census are being considered for the future.