Introduction

Within what limits is it reasonable to suppose the parameter (3 to lie? Are the data consistent with a particular theoretical value for, say, the parameter 13? Let Y r be a further observation assumed to be obtained from the same model and parameter values as the original data, but with

E (Y f ) = 7 + /Jx+. Within what limits is Y 'l expected to lie? In the theoretical discussion, it will be usual to take a family of

models as given. The task is to formulate meaningful and precise questions about such models and then to develop methods of analy­ sis that will use the data to answer these questions in a sensitive way.