If they're wearing a lap-and-shoulder belt, in this raw data, 19.4 percent die. And interestingly, wearing a lap-only seatbelt, 16.7 percent die. And actually, the theory tells you that the lap-only seatbelt's got to be worse than the lap-and-shoulder belt. And that just reminds you that when you deal with raw data, there are hundreds of confounding variables that may be getting in the way.
如果孩子戴了腰上和肩膀上的安全带， 在这份原始数据中， 死亡率是 19.4%。 有趣的是，使用仅仅是腰部的安全带， 死亡率只有 16.7%。 实际上，原则上来讲 腰部安全带应该比腰部和肩部都有保护的安全带效果差。 这个数据提醒了我们 当我们看真实的原始数据时， 需要考量成百上千的因素，它们都有可能影响最后的结果。