The caveats around children attending independent schools or schools in England are particularly relevant to local authority level results as these factors have geographical patterns.
Mae'r cafeatau ynghylch plant sy'n mynychu ysgolion annibynnol neu ysgolion yn Lloegr yn arbennig o berthnasol i ganlyniadau ar lefel awdurdod lleol gan fod gan y ffactorau hyn batrymau daearyddol.