Over blogs and Twitter, both age and gender prediction accuracies drop to a greater degree (when only using the Facebook-trained models), suggesting stylistic or content differences between the domains.
although some words no doubt have a nonlinear relationship with age (e.g., 'fiance' peaks in the 20s), we still find high accuracy from a linear model (see Table 1) and it allows for a distribution of the model in the accessible form of a lexicon.