when we think of scoring a rubric, we intuitively think that each of the possible scores as being equally likely. This is a subtle systemic bias that happens because each column in the rubric’s grid is the same width.
So what? Well, we’ve just seen that it makes just as much sense for intervals to vary in size as it does for them all to be the same size. In other words: you cannot interpret a rubric element’s scores unless you know what kind of distribution has been assumed by the author of the rubric!