It is often not possible (due to low sample size in some categories) to analyse data for more than one variable at a time, which can limit the usefulness of any analysis.
Yn aml, nid yw'n bosibl (oherwydd maint sampl isel mewn rhai categorïau) dadansoddi data ar gyfer mwy nag un newidyn ar y tro, a all gyfyngu ar ddefnyddioldeb unrhyw ddadansoddiad.