ABSTRACT
Not all multilevel data are purely hierarchical. For example, pupils can be nested within
the schools they attend, and within the neighborhoods in which they live. However, the
nesting structure may be less clear when we consider the schools and neighborhoods. It is
likely that there is a tendency for pupils to attend schools in their own neighborhood, but
there will be exceptions. Some pupils will attend schools in other neighborhoods than the
one they live in, and especially schools that are located close to the border of two
neighborhoods may be expected to draw pupils from several neighborhoods. As a result,
it is not possible to set up an unambiguous nesting of pupils within schools within
neighborhoods. We could, of course, arbitrarily set up such a model structure, but to do so
we would have to include several schools more than once, because they appear in
different neighborhoods.
