probable error
/ˌprɒbəbl ˈɛrə/noun
Statistics. The difference between the mean of a distribution and the first or third quartile, i.e. an error of such a magnitude that larger and smaller errors are equally likely.
- Now largely superseded as a measure of accuracy or consistency by the standard error. The probable error is 0.67449 times the standard error..
Origin
Late 18th century (in an earlier sense). From probable + error.