Links that are useful

https://www.statlearning.com/, a book to be downloaded to learn statistics and apply in R.

https://intro2r.com/whoarewe.html, an online book that nicely flows you through R, include also how to do a ggplot

the genomics book containing a nice chapter on interaction : http://genomicsclass.github.io/book/, where data comes from that paper : https://www.jstor.org/stable/48576004.