In the months of COVID-19 lockdown when sample sizes in some regions were in single figures, it would have had the effect of making individual establishments dominate the results.
Yn ystod misoedd cyfnod clo COVID-19 pan oedd maint samplau mewn rhai rhanbarthau mewn ffigurau sengl, byddai hyn wedi arwain at sefydliadau unigol yn dominyddu'r canlyniadau.