Social Media consultants regularly point out that the metrics used for traditional or online advertising campaigns don't apply to social media because they don't take into account the more "social" component of "social media". Metrics like "conversations started", "comments generated", etc. are often more appropriate even if they don't directly correlate (at least in the short run) to sales. However, the same holds true for "measured media" (whether traditional or online). Just because certain metrics are available does not mean that they are effective metrics.