This new study combined a large number of previous studies and concluded that a lack of social interactions ranks right up with smoking,obesity, and alcoholism as a risk factor for death.

VOA: standard.2010.07.29

And that's why, I ended up using a multiplicative factor, rather than an additive factor.

这也是为什么，我最后使用一个倍增因子，而不是用一个加法因子。

麻省理工公开课 - 计算机科学及编程导论课程节选