Anti-selection groups will argue that the eleven-plus leads to most children being labelled as failures at an early age, thereby permanently damaging their educational progress.
Then, in his blog post last week, he repeats incorrect information about the genesis of the Exchange being plagued by anti-selection, which he appears to have made up from whole cloth for an earlier blog post.
Both methods can be applied to a broad selection of objects, making them ideal candidates for anti-counterfeit detection for everything from diamonds to passports -- all that's needed to verify authenticity is an optical microscope.