Models can take many forms: a verbal description, set of mathematical equations, or segment of computer code. In this book, we are interested in a specific kind of model, probabilistic or statistical model, which represents the variability that occurs in a nondeterministic experiment.
Note
We use the term experiment in this book in a somewhat non-technical sense. For us, an experiment is any observation of an event of interest. Examples of experiments are observing the number of visitors to a website or conducting an opinion poll or clinical trial. The main characteristic of experiments, for us, is that they can be repeated and that there is randomness, that is, each repetition of the same experiment may result in different outcomes.
The models that we will consider take the form of random variables. A random variable is an idealized representation of a probabilistic outcome that has numerical results. It is important to realize that a random variable is an abstraction...