Re: @ Doctor Syntax
"Probably because the EU sets the bar so low that any objective criteria would almost certainly lead us out of the EU."
Just the attitude I worry about. If the UK GDP had dropped by 50% of pre-referendum level you'd still point to this or that and proclaim a success.
How about we can agree it's a success if UK GDP rises by 5% and a failure if it falls by 5% in 5 years, relative to pre-referendum level and adjusted for any overall change in world GDP? Or maybe a 5% increase or decrease in balance of trade? Or some measure of living standards or employment? Personally I'd be delighted if, by some such measure, Brexit were to be proclaimed a success. Delighted but astonished.
Remember the Yes Prime Minister episode where any proposal was to be accompanied by failure standards? Somehow that never caught on in real life government or political circles. What a pity.