Figure 3
From: The spatial distribution of radiodense breast tissue: a longitudinal study
Between-woman variability in regional percent density, by level of overall percent density. For each region, between-woman variability in regional percent density (PD) was estimated by the standard deviation (SD) of the PDs for all participants in each overall PD group. X, region where fewer than two women contributed to the analysis and hence the SD could not be estimated.