These intervals have been adjusted to take into account the design of the survey, and are larger than they would be if the survey had been based on a simple random sample of the same size.
Addaswyd y lwfansau hyn i ystyried cynllun yr arolwg, ac maent yn fwy nag y byddent pe bai'r arolwg wedi'i seilio ar sampl syml a ddewiswyd ar hap o’r un maint.