The term spatial statistics refers to the application of statistical concepts and methods to data that has an explicit spatial structure that is important to understanding those data. Where data is available, with associated spatial information, and the latter adds nothing to the understanding of the data, then analysis can proceed as if the data had no spatial context - i.e. as if the data was aspatial. Spatial statistics is a discipline in its own right, closely associated with traditional statistical methods and more modern computational statistics, but with the added complexity of spatial dependence - typically spatial data samples are not independent as is usually required in traditional statistical methods. Key aspects of spatial statistics are briefly discussed in the sections that follow, with more detailed specific procedures being covered in Chapter 5: Data exploration and spatial statistics.