In an e-mail to TVNewser this afternoon, an ABC spokesperson added an addendum to this post about Nightline's ratings:

"What Media Life doesn't seem to realize and therefore doesn't report is that the primary selling demographic for Nightline (and all news programming for that matter) is Adults 25-54. If they had bothered to report a complete story, they would have seen that since Ted Koppel's departure at the end of November, Nightline has maintained and continues to average the 1.4 A25-54 rating.

Furthermore, since Koppel's departure, the show has also held onto 99% of total viewers." In the 25-54 demo:

9/19 (start of season) to 11/27: 1.4

11/28 to 1/13: 1.4

> Update: 6:41pm: More total viewer data, this time from today's WSJ: "At Nightline...the average total audience dropped 9% to 3.5 million viewers for the period from Sept. 19 to Jan. 16, compared with the year-earlier period, according to Nielsen. The show's ad revenue, for a two-month period starting in September, fell 12% over the year earlier, according to TNS Media Intelligence."