Quantitative measures that can be useful in guiding the process of structuring and analysing a decision tree model are identified. These are classified according to whether they relate to the structure of the primary decision problem or the structure of the secondary or information gathering decision problem. An important question that arises during the process of developing a structural model of a decision situation is whether to encode uncertainty on an important variable directly or to model the situation further. These represent two different but complementary approaches to quantifying judgment whose use must be balanced in any decision problem. One is related to the value of modelling and one related to the value of information. The measures associated with the value of modelling are specifically useful in developing a model of the decision situation. The measures associated with the value of information are specifically useful in the analysis of the decision model. Four measures related to the value of modelling are identified. They are useful in achieving this balance between uncertainty encoding or further situation modelling.