Left panel: comparison of the average SED data (magenta points) and our broken power-law fit (magenta lines) with different literature SEDs (Clemens et al. 2008; Leroy et al. 2011) for ULIRGs. For comparison, we show the Condon (1992) model for a normal SFG. Right panel: comparison of the different goodness-of-fit tests for different models. We show the log-likelihood test and the Akaike and Bayesian information criteria. We give the average of these three criteria for reference.