used to indicate that something specified will have a powerful, though unpredictable, influence on a result or outcome
…这一因素（指对结果会产生难以预见的有力影响之物）
the feel-good factor.
幸福感这一因素。
include (or exclude) something as a relevant element when making a calculation or decision
（计算或作决定时）包括（或排除）某一相关因素
when the psychological costs are factored in, a different picture will emerge.
如果将心理成本计算在内，结果就不同了。
To figure in
包括，把…计算在内
We factored sick days and vacations in when we prepared the work schedule.
当我们准备工作时间表时，我们把病假和假期都包括在内