This is an attempt to solve all exercises included in the book 'Data Analysis Using Regression and Multilevel/Hierarchical Models' by Andrew Gelman and Jennifer Hill. The authors didn't provide a solution to most of the exercises, although for some of them you can find other solutions in some repositories in the web space (including GitHub). This is my way to thank the authors for the wonderful work they did. This book deserves more credit and I would suggest to any of you to read it and attempt your own solutions to the exercises.

I decided to use R on my solutions because libraries for doing multilevel modelling in Python are not yet mature. This shouldn't worry to much existing Python users; you should instead take this as an opportunity to learn R. I'm a long time user of both R and Python and I love them both. They both have strenghts and weaknesses.

The data for all the problems can be found at this URL: http:https://www.stat.columbia.edu/~gelman/arm/examples/

If you don't agree with one or more of the solutions I published, please feel free to send a pull request.