Photoionization cross sections, branching ratios, and photoelectron angular-distribution asymmetry parameters have been calculated for the Yb (Z=70) 4f, 4d, and 6s subshells using the relativistic random-phase approximation, the truncated relativistic random-phase approximation, and the relativistic random-phase approximation, modified to include relaxation effects. Comparisons are made between the various approximations and experimental data. Important relaxation effects for the 4f and 4d channels are noted and strong effects of interchannel coupling are noted for 6s photoionization in the region near the 4f and 5p thresholds. © 1994 The American Physical Society.