ABSTRACT
In this chapter we review the analysis of some special models that are impor tan t b o t h i n their own right and as i l lustrat ive exam ples. T h e emphasis is on situations where more than a sequence of univariate analyses is needed. A s we have mentioned previously, decomposable independence structures are expressible v i a a sys t em of univariate regressions and can be analysed v i a a sequence of univar iate analyses, often least-squares regressions or logistic re gressions. T h e graphica l representation is equivalent to a directed acycl ic graph. W h e n the most efficient analysis is not equivalent to such a series of univariate analyses it is, of course, desirable that the ex t ra complicat ions of any more elaborate analysis undertaken should lead to a genuine gain i n interpretat ion.
