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.
In fact, in 2015, you're going to pay about 75% more to fly around the holidays than you would pay on the same route at any other time! But there are still a few ways you can save on airfare this season. The Hopper data science team found out when you should be flying and when plane tickets will be cheapest ...