Nominal, Ordinal, Ratio, Interval...? Need help.

I am having a really hard time with deciding whether things are nominal, ordinal, ratio, or interval. I was given four problems and asked to list their highest level of measurement. Here are my problems and what I have done so far:

1. Size of goups dining together.

I want to say that this one is interval, because the differentces are meaningful. But couldn't it also be nominal, since the sizes of the groups are being placed in categories?

2. Ages of the diners.

I believe this one might be ratio, because there is a true zero and the differences are meaningful...for example, a person can be twice as old as someone else.

3. Age grouping of diners: Children, young adult, middle aged, senior.

I think that this one might be ordianal, since they people are placed into categories. Also because it might be hard to determine the differences between the categories.

4. Length of time a diner waits for a table.

I believe this might be ratio becuase there is a starting point. But, the diners do not all start waiting at the same time so I'm not sure if it can be ratio and should be interval instead.

Any help and explanations for answers would be greatly appreciated!! I just can't seem to figure these out!! Thanks!


TS Contributor
1. is ratio, even though you theoretically can't have a group of size 0, but differences are consistent across the entire scale, and you can make statements such as "group A is twice the size of group B"

You're correct on all the others. Yes, 2. is ratio, 3. is ordinal, and 4. is ratio.