Finally, to establish the accuracy of our predicted transport properties we performed a detailed comparison to selected measurements from experimental studies on Bi 2 SeO 2 and Bi 2 TeO 2 (Section S1.1, SI). The calculations predict the measured transport properties of single-crystal Bi 2 SeO 2 to within a factor of two. However, comparison to measurements on more typical consolidated powder samples of Bi 2 SeO 2 and Bi 2 TeO 2 show larger variability, particularly in the predicted power factors, which we ascribed to "energy filtering" and "carrier pocketing" effects. . We therefore suggest that these calculations may serve as a useful reference point for assessing the quality of consolidated powder and/or thin-film samples, and for determining the impact of sample morphology on the electrical transport.