  We discuss several aspects of creation of adequate mathematical models in
other sciences. In particular, many difficulties stem from great complexity of
the source systems and the presence of a variety of uncertain factors. We
illustrate the effect of uncertainty on the known consumer demand model. We
conclude that not every uncertainty can be represented by a random variable,
and that these concepts are not equivalent. We discuss also the role of
different information concepts in mathematical models. We give additional
illustrative examples of models of quite complex systems.
