If you’re a producer on a new network TV show, and you’re still churning out episodes come Thanksgiving, this is indeed a time to give thanks.

You’re not on the phone with your agent looking for a new gig, and those studio paychecks will buy a lot of Christmas cheer.

But if you’re a viewer, it’s a more tenuous time. After all, you’ve invested several hours in one of these new programs, knowing that the big payoff won’t come until next spring, when the characters and story lines play out to a satisfying season-ending conclusion — if it lasts that long.

When I’m on my social networks, the question I get asked more than any other is: Should I keep watching (your favorite new show here), or is it about to get canceled?

We’ll get to those shows in a moment. First, though, it’s important to understand that executives at the major networks are not judges on “America’s Got Talent.” They don’t make snap decisions. They are risk managers overseeing portfolios with assets that start in the multimillions and escalate to $100 million a year for established hits.

They don’t, contrary to legend, suffer from itchy trigger fingers. They cancel only after taking several measures of a show: budget, ratings trends, the quality of upcoming scripts and what’s waiting in the wings. When a show gets a quick hook, as NBC’s “The Playboy Club” did this fall, you can bet that all these factors are going south.

(By the way, if you’ve wondered why cable TV shows almost never get canceled mid-season, it’s because they have shorter seasons and smaller budgets and are targeted at niche audiences. All of this reduces financial risk, which allows executives to take bigger creative risks. The top of the cable ratings is loaded with edgy fare: AMC’s “Walking Dead,” FX’s “Sons of Anarchy” and “American Horror Story,” Comedy Central’s “Tosh.0” and Bravo’s “Real Housewives of Atlanta.”)

Handicapping a network show’s odds of survival is kind of like guessing whether you’ll enjoy Thanksgiving: it all depends on the relatives.

For instance, in a typical TV ratings story you’ll learn how a show did relative to other shows in the same time period and whether it’s trending upward or downward as the season progresses. But those are only two relative measures of a show’s success.

A more telling measure, I would argue, is how the show is doing relative to other shows on the same network.

In the accompanying box, I’ve used each network’s average prime-time rating for Sunday through Thursday — when viewing levels are highest — as a baseline. Anything that falls significantly below that line is probably not performing up to that network’s standards. (I look at ratings for viewers ages 18-49 because that, broadly speaking, is the audience advertisers care about.)

For instance, ABC’s teen soap “Revenge” and Fox’s dino-drama “Terra Nova” are both averaging a 2.7 rating. In other words, each show is watched by 2.7 percent of the 18- to 49-year-old population. That is only 7 percent off the 2.9 rating that third-place ABC averages during the week, but it’s 21 percent below the 3.4 average for Fox, TV’s top-rated network.

Based on this data, and the fact that “Terra Nova” is laden with expensive CGI work, I’d say the show with T-rexes is facing extinction while “Revenge” may get the last laugh.

CBS, meanwhile, placed a big bet this season on dramas about people with exceptional talents: “Unforgettable,” “Person of Interest,” “A Gifted Man” and returning show “The Mentalist.” But they’re all performing well below the average for crime-drama-heavy CBS. Two of these four genius shows might make it to next season, but that’s just my guess (and I’m no genius).

Then there’s NBC.

How far has the former No. 1 network fallen? Put it this way: If not for Sunday, NBC would probably be in fifth place behind Spanish-language Univision.

In fact, every single prime-time NBC show other than sports is at or below the network’s average of 2.9. That number, of course, is skewed by “Sunday Night Football,” far and away television’s most popular program this fall.

But using NBC's mean median rating instead of its average rating effectively excludes the outlier of NFL programming and yields a number that more accurately reflects NBC’s woeful overall lineup.

The median for NBC just 2.0 (the rating for the unfunny comedy “Up All Night”). To give you some idea, almost nothing is allowed to stay on ABC, CBS or Fox if it scores below 2.0 in the 18-to-49 demographic. Yet half of NBC shows are in this no-man’s land — or were. Last week “Prime Suspect” was shut down and “Community” went on hiatus, though it will probably return.

I can’t imagine running an NBC station is much fun these days. But Mike Vrabac, general manager of Kansas City’s KSHB, said that the “Today” show and his local newscasts — where KSHB makes most of its money — are up compared to a year ago.

“We’re worrying about what we can control,” Vrabac said philosophically. “We do have the Super Bowl and the Olympics, and NBC has ‘The Voice’ coming back in January. I’m hoping that if we get a little uptick it will be better.”

One last relativity variable to consider is the weekend, or as I call it in the accompanying box, “The Weak End.”

Because the number of people who even watch prime time on Friday and Saturday has declined steeply, networks are loath to spend any money on those nights. That means reruns and cheap-to-produce shows.

No network enjoys much of an advantage on weekends, so what few original shows there are on those nights I’ve thrown together. Anything below the mean median rating that isn’t reality TV is probably toast.

Of course, things could always change in the next 31 weeks. But don’t be surprised if many of these underperforming shows are gone by season’s end.

It’s your DVR and your free time. Spend it wisely.