Labour's rating could have declined by 5% or 10% or even collapsed entirely

In this disgracefully dishonest article on immigration Barbara Roche (Chairperson of the Migration Matters Trust) argues that apologising for open-door immigration has only managed to improve Labour's rating by one per cent:  http://www.progressonline.org.uk/2014/09/22/time-to-stop-saying-sorry-on-immigration/

This is of course a bogus use of statistics.

Without an apology Labour's rating could have declined by 5% or 10% or even collapsed entirely.