When I don't want students spending a lot of time memorizing things, I simply provide supplemental information on the exam itself.
For example, imagine a course textbook lists 12 reasons why something might happen. Rather than expecting them to memorize all 12, I might list all 12 on the exam, with an application question such as:
The book lists these 12 causes; which of the 12 is most likely to lead to a catastrophic failure? Explain.
In the case of a statistics class where "it is important to understand rather than know," and, "knowing statistical formulas won't help if you haven't understood how to apply them," you could simply compile a list of formulae from the course textbook and put them on the last page of the exam.
By the way, I agree with Moriarty's comment: "The act of carefully constructing this summary sheet is usually much more useful than the notes on it." My approach doesn't have this benefit, but it does have a few advantages of its own. For one, a student is less likely to get a better score simply because of a better-prepared cheat sheet. For another, the student might focus on understanding the material at a higher level instead of transcribing lower-level details.
My general rule is: If something is hard for me to remember without looking it up, then I don't expect students to memorize it for an exam. I will supply it instead.
Here's another idea to consider. (I haven't used this one, but I had a professor who did, and I admit I liked his reasoning.)
One professor of mine had a custom of administering open book, closed notes exams. (In other words, you could use your book, but not a cheat sheet.) Why this way, instead of the other way around? Because, he said, "Most students won't keep their cheat sheets, but a lot of them will keep their textbooks." There were no restrictions on writing inside the margins or the back cover (in fact, that practice was encouraged). Sure enough, I still have a book from his course, and I just opened the front cover, and found my cheat sheet still intact, with plenty of complex equations and hyroglyphics in my own handwriting.
As more and more campus bookstores offer e-readers, this approach might become outdated. But I still think it's worth sharing; I always appreciated how this particlar professor was always looking years down the road, as opposed to just the end of the term.