In the links below, you find some notes I wrote at some point for my own quick references or as a preparation for classes in statistics and mathematics. They are very condensed and more useful if you already know the subject. Few of them, as the notes on convex optimization, present the intuition behind the concepts as well. I have found them useful when I needed a quick refresh of some concepts. They are by no means complete and from time to time I update them with additional content. If you find any incorrection or have any suggestion feel free to send me an e-mail.