Importance dendrogram showing the most informative multifactor trends in average condition score (BCI_ave). The condition of the bridges has been banded from very good to very poor. Each pie chart represents the distribution of the condition bandings within the subpopulation below that point in the tree structure. The top ‘Whole stock’ pie chart represents the distribution of condition in the whole stock. The red text on each branch of the tree represents the attribute that the data set has been partitioned by at that level, and the black text represents the value of the attribute. The size of each node (pie chart) has been drawn inversely proportional to its entropy, such that the most informative partitions can be readily identified