English: 1 year rolling average
Welsh: cyfartaledd treigl blwyddyn
Subject: Cyllid ac ystadegau
Welsh definition: A 12-month rolling average, or moving average, is simply a series of 12-month averages over multiple consecutive 12-month periods.
Notes: Defnyddir y term Saesneg “moving average” hefyd ar gyfer yr un cysyniad ystadegol. Nid “y cyfartaledd dros flwyddyn dreigl” yw’r ystyr.