Dunkelziffer

Etymology
. Colported first in criminology in 1908 by the PhD thesis Unverbesserliche Verbrecher und ihre Behandlung p. 28 of Shigema Oba, a Japanese jurist moving 1905 to Germany for studying Western law, on the model of alleged statistician English which according to current corpora seems either entirely made up as such or merely heard in some lecture (but rather false memory since he neither hyphenated it in a likely manner nor translated it correctly, were it to have existed).

Noun

 * 1)  dark figure estimated number of unreported cases

Usage notes
Used more generally than, which specifically refers to unreported cases of crime. is now the preferred term in criminology to describe a range of uncertainty.