by a factor of
（1）The amount of energy used has gone up by a factor of eight...
[原译]所耗能量已经增长了八倍……(《柯林斯伯明翰大学国际语料库英汉双解词典》,上海译文出版社,p.672)
(2) Cases of leukemia in the area near the nuclear reactor have risen by a factor of four.
[原译]在核反应堆附近的地区,白血病的病例增长了四倍。(《英汉双解剑桥国际英语词典》,上海外语教育出版社,p.869)
原译(1)将 has gone up by a factor of eight 译为“增长了八倍”，原译(2)将 have risen by a factor of four 译为“增长了四倍”。请问这种译法对吗？
上面两部词典的原文均明确指出“If an amount becomes larger or smaller by a factor of a particular number, it becomes that number of times larger or smaller . . .”。我们在 n times more than 和 as much as 诸条目中已经证明，A is n times larger than B. = A 是 B 的 n 倍或 A 比 B 大 n - 1 倍。同样，A is larger by a factor of n. = A 是 B 的 n 倍或 A 比 B 大 n - 1 倍。其中的 be larger (greater, more) 可以换成动词，如 exceed, rise, go up 等，其意义不变。因此，上面译文中的“八倍”应改为“7 倍”，“四倍”应改为“三倍”。
by a factor of 亦可与表示减少的词语连用。但是,根据汉语的表达习惯,不可译为减少 n -1 倍,而应译为减少 或减少到(原数的) 。
The equipment under development will reduce the error probability by a factor of 7. 正在研制的设备将使误差概率降低6/7。(亦可译为:降低到原数的1/7)