If a member of your family or a relative is a resident in the home, I suggest you contact your local social services office, and speak to somebody in confidence.
I don't know the law's on exact ratio levels sadly, but once did have an issue and a concern with staffing levels at the home my late father was in.
They had a burglary in which a large TV was stolen one night, whilst the staff were upstairs, smoking and drinking.
I got social services involved when I managed to get into the home un-challenged one night, and found the staff all watching a portable TV in a rest room.
6 people losted there job's and the home was put on the watch list.
These home's take every penny off the residents and offer often sub-standard care, from experience no two homes sadly are the same, some are good and some are bad.
My Advice : If in doub't ask the professionals at social services, after all that's what they get paid for !