Regarding the first one (Introductory Statistics) what would you say the pre-requisites are? I'm not much of a mathematician, in fact I might even need to brush up on high school math by now, but I've thought about statistics for a while now. Is it approachable or would I have to study up to college level?
It is very approachable. If you know the difference between mean and median then you know enough to study the book.
It is written as a textbook for graduate biology students to help with their research, so it doesn't assume much mathematical knowledge. It also contains exercises (with answers) at the end of each chapter, really helps to consolidate the newly acquired knowledge.
