Is “distance” an ordinal variable?

I have an independent variable (distance between two stimuli) with 6 levels, but the levels are not equally spaced (e.g. 10, 15, 25, 35, 45, 60 pixels). The distance between two stimuli is important for me (I want to compare the performance in 10 pixels to performance in 60 pixels).

I am confused because I know that ordinal variables are typically non-numeric, and that the differences between points in the scale are not meaningful. But I also know that interval scale is where the differences between points on the scale are measurable and exactly equal.

If the differences between the points were equal, I would think that the variable is on an interval scale, but now I am not sure.

Would this variable be ordinal in this case?

• It might depend on your problem, but that distance is a numerical variable, not a categorical one. When dealing with a numerical distance you are taking in account both order and distance between values. "Ordinal variables" are just categorical variables where there is an order between levels, but not a meaningful distance between levels. However, to take profit of the advantages of numerical variables, you need to analize your data using tools suited for numerical variables. – Pere Jun 4 '19 at 12:03