If we have 10 fixed values of X and the corresponding 10 groups of Y values; so we can say that there are 10 Y subpopulations .
SUBPOPULATION
Meaning of SUBPOPULATION in English
Sean Woo's Finance, GIS and real estate English glossary. Английский глоссарий по ГИС(Географическая информационная система) и недвижимости Sean Woo's Finance. 2012