Which scale is most appropriate for measuring weight?

The most appropriate scale for measuring weight is the ratio scale. This is because ratio scales possess all the characteristics of an interval scale, such as order and equal intervals, but they also have a meaningful absolute zero point. In the context of weight, an absolute zero means that zero weight indicates the complete absence of weight, allowing for the comparison of magnitudes and the calculation of ratios.

For example, if one object weighs 4 kg and another weighs 2 kg, one can say that the first object is twice as heavy as the second. This ability to form meaningful ratios and to calculate differences, along with the fact that zero has an absolute meaning, distinctly characterizes the ratio scale, making it the most suitable choice for measuring weight.

In contrast, the other scales do not offer these same properties. An ordinal scale ranks items but does not convey the magnitude of differences between them, a categorical scale classifies items into categories without any inherent order or distance, and an interval scale has equal intervals but lacks a true zero point that allows for meaningful ratios. Thus, these alternatives are not applicable when measuring a continuous and quantifiable characteristic like weight.