if you don't have any trust in evidence-based research, where do you get your information from? How do you make a judgment on anything you don't have direct experience of?
Good point 
I certainly do take in data and studies, however in this area research, data and statistics are famously poor. So its a small part of my overall impression.
I am not sure how anyone records anyone from the EU coming into the country to live for a short while as Corcory said,in over crowded digs, then leave again or move on. There are vast networks all around the UK of this same pattern, over crowded - often vile digs, there is no records or these people, often their English is poor or non existent, so I do look at studies, but with a healthy dose of realism, that there is actually no system in place to accurately count people.
But, if you can show me a cast iron infallible system, then yes I would look at it, and see whether I thought it was better to take it on board more.