"Net migration"

Inside the migration statistics sausage machine.

If you are concerned about pressure on housing and public services, then it is sensible to focus on net migration. On the other hand, if you care about "integration" -- whatever that means -- then a reduction in net migration may imply a greater overall churn rate; you might want to reduce immigration plus, not minus, emigration. You might also care about who enters and who leaves.

All the immigration anecdotes I have heard suggest that in the attempt to reduce net migration, pressure is being put on the softest targets -- e.g. students. Typically, these are also the most desirable migrants. That is what you would expect if you think that migration policy follows a pattern where the rhetoric aims at the median voter, but policy is really driven by employer demands.