Two types of measurements of lung nodules are shown during repeated testing. The ribbon map was used to describe the stability of repeated measurements or reproducibility. Straight lines, such as the yellow lines for the IILS, indicate that the IILS was always repeatable, and the fluctuations of the blue or red lines, Expert1 or 2, quantify the stability in the opposite direction. That is, greater amplitude resulted in worse reproducibility. (a-d) for size and (e-f) for density. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)