I am a programmer who, in a past life, used the products RS/1, RS/Explore, and RS/Discover in a manufacturing engineer career. Now, years later, I would like to do some multivariate regression on some real-world data (sales data from my wife's store). The point would be to highlight what sales days are truly exceptional, not just part of the normal distribution, after taking into account month, day of week, weather, etc.
If I still had access to RS/1 and associated products, I'd know how to do this, but that is not the case, so I'm thinking I'd want to use R. However, most R tutorials I have found just cover the very basics, and don't get to the point of multivariate regression. Can you recommend an R tutorial that takes one past the basics of plotting a histogram, etc. into in-depth analysis of real-world ad-hoc data, presumably using multi-variate regression?
Thanks!