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These exercises are based on the textbook “Digging Numbers” by Mike Fletcher and Gary Lock (ISBN 978-0947816698). This book is an introduction to statistics written for archaeologists by archaeologists. It consists of four parts, the third being about practical examples of application using known commercial statistical software. These pages are meant to provide a “translation” of the same exercises using free software.
Please bear in mind that this tutorial is not a substitute for a complete book of quantitative archaeology or statistics. Currently it's going to be hard to follow the tutorials without having Digging Numbers with you. Maybe in the future we will add more content to this book, but at the moment it's quite useless if taken alone.
Our first software choice is the
R statistical suite.
R (http://www.r-project.org/) runs on a variety of platforms, including GNU/Linux, MacOS X, Microsoft Windows and others. Installation should be straight-forward in most cases. On some platforms,
R is provided with a basic GUI, but we will be using the command line, because it is more powerful and gives access to all the available options. Moreover, the command line interface is the same on each platform. Our examples are based on a GNU/Linux system, because we really like free software
Anytime you need to look at the documentation, you can use the
help(command.name) function inside the
R environment, which gives you a general overview of the command you asked for, the available parameters, bibliographic references and examples. Here's an example:
These pages deal with entering commands typing with your keyboard. When you start
R, you get the so-called prompt. It's
R's way to say that it's ready to accept your commands.
R prompt looks like this:
What you type goes after the
From now on, text that comes formatted like above means “this is a command”. We won't be omitting the initial
>, so you can't copy & paste commands straight in the
R window, but rather you must type. This is not as bad as it sounds.
The authors of the book included a dataset that contains various measurements and data about 40 spearheads from English archaeological sites. Example data used here are the same used in Digging Numbers itself, but we can't provide the complete dataset. We are looking for an alternative free dataset to use along the exercises without copyright worries.
However, before a new dataset is found, it shouldn't take much to copy the entire dataset in a standard CSV file, such as:
Note that character strings are between
" while numeric strings are not.