What defines ratio data in biostatistics?

In biostatistics, ratio data is defined by the presence of a meaningful zero point. This means that zero does not simply represent an absence of measurement but signifies a complete lack of the quantity being measured. For example, in the case of weight, a weight of zero indicates that there is no weight present. This meaningful zero allows for the comparison of ratios; a weight of 10 kg is twice as much as a weight of 5 kg, and the interpretation of such comparisons is valid due to the existence of this zero point.

Other potential characteristics of ratio data include the ability to take both positive and negative values; however, the critical defining feature is indeed the meaningful zero. This allows for a full range of scale operations, including multiplication and division, which are central to statistical analysis and interpretation. The other mentioned characteristics might be relevant in varying contexts but do not capture what fundamentally distinguishes ratio data within the framework of biostatistics.