The
theory of statistics provides a basis for the whole range of techniques, in both
study design and
data analysis, that are used within applications of
statistics. The theory covers approaches to
statistical-decision problems and to
statistical inference, and the actions and deductions that satisfy the basic principles stated for these different approaches. Within a given approach, statistical theory gives ways of comparing statistical procedures; it can find a best possible procedure within a given context for given statistical problems, or can provide guidance on the choice between alternative procedures.