脑化指数和相似的脑部身体质量比（Brain-to-body mass ratio，脑质量与身体质量的比值）比起来为较好的指标，因为它考虑了异速生长（Allometry）的因素。脑化指数的关系与公式只适用于哺乳类，不适用于其他动物。
英语百科
Encephalization quotient 脑化指数
Encephalization quotient (EQ), or encephalization level is a measure of relative brain size defined as the ratio between actual brain mass and predicted brain mass for an animal of a given size, which is hypothesized to be a rough estimate of the intelligence or cognition of the animal.