Reddit mentions of Design and Analysis: A Researcher's Handbook (4th Edition)

If you did not struggle with stats in undergrad, I would not worry about it, to be honest.

I was also out of school for 4 years before starting and I did not have any difficulties with the statistics classes we started with. My intro stats classes in grad school covered much of the material that we did in undergrad, just more in-depth, more variations on the tests, and we were expected to understand the math behind the equations more fundamentally.

If it happens to be helpful, my first two quarters of stats had these textbooks:

Statistical Methods for Psychology - https://www.amazon.com/Statistical-Methods-Psychology-David-Howell/dp/0495597848/ref=sr_1_2?ie=UTF8&qid=1523397437&sr=8-2&keywords=statistical+methods+for+psychology&dpID=51T8KyWmliL&preST=_SX218_BO1,204,203,200_QL40_&dpSrc=srch

and

Design and Analysis: A Researcher's Handbook - https://www.amazon.com/gp/product/0135159415/ref=ox_sc_sfl_title_3?ie=UTF8&psc=1&smid=A17LQ734FP5YDC

Please do not pay lots of money for them.

If it is at all helpful (aka not stressful), I also took a pic of my "map of statistical analyses", which basically has the non-fancy statistics - https://imgur.com/xw6cGxM Do NOT look at this and be like "oh no!". Look at it and be like, "Oh yeah, an ANOVA (Analysis of Variance) is a thing that exists."

If you do decide to spend a little time reviewing, I strongly recommend not spending a lot of time on it and not feeling worried about it. This is your time to unwind a bit and you should enter your program feeling chill and relaxed if it all possible. You got it because you are smart, passionate, and hard working, and, as a result, you will do fine in statistics.