In a weight-balanced tree, the _____ of a node is defined as the number of nodes in its left subtree divided by the number of nodes in its right subtree.

In a weight-balanced tree, the balance factor of a node is defined as the number of nodes in its left subtree divided by the number of nodes in its right subtree. The balance factor is an important measure used to maintain the balance of the tree during operations such as insertion and deletion. A well-balanced tree generally performs better, as it ensures that operations like search, insert, and delete can be executed in logarithmic time complexity. The optimal balance factor for a weight-balanced tree usually lies within a specific range, which helps in determining when rotations or restructures are necessary to maintain tree balance.