Specifically, items that differed by more than 0.5 standard deviations (of the retrospectively recalculated item difficulty scale) from their 2023/24 value were removed from the analysis.
Yn benodol, cafodd eitemau a oedd yn wahanol o fwy na 0.5 o wyriad safonol (o'r raddfa anhawster eitemau a gafodd ei hailgyfrif wedi hynny) i’w gwerth 2023/24 eu dileu o'r dadansoddiad.