In this stage, you actually perform the analysis/inference with selxavg3-sess by passing it the configuration and the session that you want to analyze. selxavg3-sess customizes the analysis for that session based on what it finds in the hierarchy, builds the design matrix and performs the analysis. Breaking the First Level Analysis up into these two stages (setting up and running the analysis) assures that all sessions are analyzed in the same way.
selxavg3-sess -analysis <analysis name> -s <subjid>