Fig. 4 

Concordance between the classification of a absolute dense area/volume, b percent dense area/volume and c non-dense area/volume into quartiles using STRATUS and Volpara measurements. Note: Agreement between the STRATUS and Volpara measurements for classifying women into mammographic density quartiles was calculated using Cohen’s weighted kappa. Weighted Kappa, κw values for dense area/volume, percent dense area/volume, and non-dense area/volume were 0.28, 0.35 and 0.50, respectively