The effects of the writers strike are starting to show up in year-to-year ratings comparisons: In a week when Fox dominated thanks to “American Idol” and to a good start for lie-detector reality series “Moment of Truth,” the broadcast industry as a whole limped across the finish line.

This week makes for a clean year-to-year comparison, since it features no football. Also, the same frame from 2007 featured original episodes of such shows as “Grey’s Anatomy,” “Desperate Housewives” and “CSI” that exhausted their final fresh episodes for this season earlier this month.

Although increased DVR penetration nationally makes year-to-year comparisons a bit misleading — more viewers are getting caught up in the week following a show’s premiere — it’s hard to ignore the declines. The top five English-language broadcasters were down a collective 21% in adults 18-49 vs. the corresponding week of a year ago, according to Nielsen. (In most weeks earlier this season, that falloff was closer to 10%.)

ABC slid 23% and CBS 26%, while Fox was off about 15%. CW, meanwhile, hemorrhaged a full 50% of its year-ago 18-49 audience.

NBC, the most aggressive with reality replacements and with the fewest scripted hits to begin with, has held up the best among the broadcasters this month — down 7% vs. the same week a year ago. And in the four weeks of 2008, it ranks second to Fox in 18-49.

Meanwhile. the combo of Univision — a Spanish-language net unaffected by the strike — and MyNetwork, which doesn’t air any firstrun scripted programming, was up a bit year to year. These nets, as well as cable newsies getting a boost from a hot presidential election cycle, seem to be the biggest beneficiaries of the 3-month-old writers strike.

Also taking advantage was Sunday’s TNT/TBS simulcast of the Screen Actors Guild Awards, which was up a bit year to year and drew a slightly larger aud (6.1 million viewers) than NBC’s coverage of the Golden Globes press conference two weeks earlier (6 million).

Overall for the week of Jan. 21-27, Fox cruised to victory in adults 18-49 with a 4.5 rating/12 share, followed by NBC (2.6/7) and ABC and CBS (both 2.3/6). Univision ran fifth, with cablers TBS and USA tied for sixth (1.0/3).

Fox also won in other key categories, ranging from adults 25-54 (4.9/12) to those 12-34 (4.1/12), and easily beat runner-up CBS among total viewers (11.7 million to 9.3 million).

The net has also opened up a healthy 16% advantage over its rivals for the season’s lead in 18-49 (3.7 to a 3.2 for ABC, CBS and NBC), and will certainly pad that with the current week, which is capped by the Super Bowl.

Fox claimed the top three shows of the week in numerous categories, with “American Idol” segs on Tuesday (11.8/29 in 18-49, 29.27m) and Wednesday (10.9/28, 27.09m) and Wednesday’s preem of “Moment of Truth” (10.2/24, 23.05m).

“Moment” was the highest-rated premiere of the season (Daily Variety, Jan. 25), and retained an impressive 94% of its 18-49 lead-in from “Idol.”

Fox also carried Thursday in 18-49, thanks to two hours of “Are You Smarter Than a 5th Grader” (3.2/9 in 18-49, 10.42m from 8 to 10 p.m.), marking the first time the net has captured the night in the demo for two straight weeks in-season.

Also winning were Saturday’s combo of “Cops” (2.3/7 in 18-49, 6.49m at 8:30 p.m.) and “America’s Most Wanted” (2.2/6, 6.39m).

On the scripted side, “House” dominated its Tuesday hour with a repeat (5.0/12, 13.91m), and rookie “Terminator: The Sarah Connor Chronicles” (3.6/8, 8.66m) placed second in demos on Monday, though it has cooled off since its hot start.

NBC had good showings from firstrun Tuesday drama “Law & Order: SVU” (4.6/12, 12.98m) as well as unscripted series like “American Gladiators” (4.2/10 in 18-49, 9.99m), “Deal or No Deal” (4.4/10, 14.24m), “The Biggest Loser” (3.7/9, 8.97m) and “The Celebrity Apprentice” (3.7/9, 8.68m); latter stood as Thursday’s top show in 18-49.

Net was dragged down by weak results Saturday and Sunday, though, for the U.S. Figure Skating Championships, which moved over to the Peacock after a long run on ABC/ESPN.

ABC’s quiet week was led by “Extreme Makeover: Home Edition” (5.1/12 in 18-49, 13.55m), whose two-hour edition Sunday ranked as the week’s No. 4 show in 18-49. There was little to cheer elsewhere, though, as the net was hurt by low-rated repeats of “Grey’s Anatomy” and “Desperate Housewives” on Friday, while Monday’s “Dance War” saw its lowest scores to date (2.6/6, 9.84m).

CBS was paced by repeats of “Two and a Half Men” on Monday (4.0/9, 11.58m) and “CSI” on Thursday (3.3/8, 13.27m), while a Garth Brooks concert spec did pretty well on Friday (2.1/6, 8.16m). On Sunday, the Hallmark Hall of Fame debut of “The Russell Girl” wasn’t a great demo performer (2.2/5 in 18-49) but drew a solid 12.73 million viewers overall.

CW had a couple of decent performers in “Friday Night Smackdown” (1.4/4 in 18-49, 4.88m) and Tuesday’s “One Tree Hill” (1.3/3, 3.04m). But the net continues to get buried on Sunday with a pitiful 29th- place finish in 18-49 for its lineup that includes original programs “CW Now” and “Life Is Wild.”

MyNetwork wasn’t too far behind CW for the week in 18-49 (0.5 to 0.7), led by Tuesday series “Jail” (0.8/2, 1.69m). And the net got off to a good start in the current week with “The New Harlem Globetrotters: A New Generation,” which set net records for a Monday in key male demos as well as total viewers (2.4 million).

In the tight evening news race, ABC’s “World News” (2.5/9 in 25-54, 9.81m) edged ahead of NBC’s “Nightly News” (2.4/8, 9.64m), with the former’s Charlie Gibson-fronted program logging its best numbers in about a year.

And in cable for the week, Disney Channel’s original movie “Minutemen” was the week’s most-watched program (6.49 million), peaking with 7.3 million in its final quarter-hour. Pic, starring Jason Dolley of the net’s “Corey in the House,” drew about one-third of the kids 6-14 aud watching television at the time.

Also topping 5 million viewers on cable for the week were a pair of “Zoey 101” episodes on Nickelodeon (5.72 million at 8 p.m. and 6.02 million at 8:30 p.m.), while History Channel scored with its “Life After People” spec on Monday (5.40 million), and USA’s “Monk” pulled in 5.32 million.

“Life After People” was also cable’s No. 1 show of the week in adults 18-49 (2.1/5), while the top scripted series were USA’s “Psych” (1.6/5) and FX’s “Nip/Tuck” (1.6/4). Another series standout was Bravo’s unscripted “Project Runway” (1.7/4).

Also noteworthy was an improved perf for the Miss America pageant, which shifted to cabler TLC. Its Saturday night telecast “Miss America Live!” averaged a hearty 3.63 million viewers, up 52% from last year (2.84 million and 18% above 2006 (3.07 million), both on CMT. Net also noted that this year’s telecast attracted a median age of just 37, compared with 44 a year ago.

* * *

On Monday of the current week, President Bush’s final State of the Union Address averaged a combined 37.52 million viewers on six broadcast networks and three cable news outlets. (Nielsen doesn’t break out individual network averages, though NBC appeared to draw the largest aud of any carrier based on affiliate-based preliminary results.)

The cume is down a rather sharp 18% from the 2007 address, which brought in 45.49 million viewers. The largest aud during Bush’s two terms was the 62.06 million who gathered for his 2003 address.