What is one limitation of an interval scale?

An interval scale is indeed characterized by the presence of equal intervals between values, allowing for meaningful comparisons of the magnitude of differences. However, one significant limitation is that it lacks a true zero point, which means that zero does not indicate the absence of the quantity being measured.

In practical terms, this means that while we can say that the difference between 20 degrees and 30 degrees is the same as the difference between 50 degrees and 60 degrees, we cannot say that a temperature of 0 degrees (Celsius or Fahrenheit) means there is no temperature. This absence of a true zero makes it impossible to make absolute statements about ratios. For example, one cannot claim that 40 degrees is "twice as hot" as 20 degrees because the zero point on these temperature scales does not represent a total lack of heat.

This distinctive feature differentiates interval scales from ratio scales, which do have a true zero and can express ratios meaningfully. Other options are not aligned with the properties of interval scales: they can indeed be used for interval comparisons, they can be quantitative (not always qualitative), and they can express differences between groups, albeit without a true zero point.