[mistermcgruff]

A semester of linear algebra (or just a willingness to Wikipedia a few things) plus Excel experience is all you need.

That said, the book does require a lot of effort, because the techniques are worked through step by step.

But once you learn all the guts of the algorithms, you never have to implement them again! The last chapter moves the reader into R package land with the confidence that you now know what those packages are basically doing and what to watch out for.