double-blind study - an experimental procedure in which neither the subjects of the experiment nor the persons administering the experiment know the critical aspects of the experiment; a double-blind procedure is used to guard against both experimenter bias and placebo effects.
No they get more expensive, airlines will always advise you to book in advance to take advantage of their best fares. Sometimes they do a special deal but not within a week of flying. I would try another airline or make different plans.
The Guardian also admits that pretty much every other flight out there is significantly more expensive, so Norwegian's cheaper base fares do pay off. And if the idea of flying budget across the Atlantic gives you back pain, don't fret.