ELASTICITIES OF CONSTRAINED GRAVITY MODELS*
通过系列例子展示，双重约束重力模型的流量弹性的符号和大小取决于平衡方法，因此平衡过程应被视为重力理论的一部分。
ABSTRACT Doubly constrained gravity models require a balancing procedure to make estimated origin and destination totals consistent. We show through a series of examples that not just the magnitudes but even the signs of derivatives and elasticities of gravity model flows depend on the specific balancing procedure used. Hence, if such elasticities are regarded as meaningful, then the balancing of origin and destination totals must be regarded as an integral part of the gravity theory itself.