Shane Nyman

USA TODAY NETWORK-Wisconsin

There's no doubt about it: "Making a Murderer" is hot.

The true crime documentary series arrived on Netflix in December and seems to have captured the attention of the masses. The Steven Avery case didn't just find its way into holiday conversations, the chatter has spread wildly on social media and invaded late-night TV, 24-hour news networks and, seemingly, every corner of popular culture.

Whereas most forms of entertainment come with easy-to-understand performance stats — new movies have box office tallies, television shows have Nielsen ratings, music has record sales, downloads or streams — Netflix doesn't reveal how many people are watching its content.

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It seems like everyone has knocked out at least a couple of "Making a Murderer" episodes, but how big, really, is the audience?

Forbes' Paul Tassi recently said the 10-episode series from filmmakers Laura Ricciardi and Moira Demos is Netflix's most significant show ever.

"I have never seen a show consume the pop culture conversation like this outside of when programs like 'The Walking Dead' and 'Game of Thrones' kill off a major character," Tassi wrote.

Despite his claims, evidence is scarce.

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With traditional broadcast TV, we get Nielsen ratings that tell us that about 38 million people watched the Green Bay Packers defeat Washington on Sunday, or that 18.5 million tuned in to the Golden Globes.

For Netflix programming, however, it's nothing but a guessing game.

"As of right now … there is nothing reliable as far as I'm concerned that says this is how many people watched a show on Netflix," said Joe Adalian, who has been writing about TV for 20 years and is West Coast editor for Vulture.

Timeline: History of the Steven Avery case

The series focuses on the conviction of Steven Avery and his nephew Brendan Dassey in the 2005 murder of 25-year-old Teresa Halbach. Two years before the homicide, Avery had been exonerated in a rape case for which he served 18 years in prison.

There are other numeric comparisons that might offer a ballpark figure on viewership of "Making a Murderer."

"(Netflix) is in about as many homes now as HBO," Adalian said. "It's not unfair to extrapolate that a decent percentage of Netflix subscribers have watched 'Making a Murderer' and that that probably puts it on par with some top HBO shows."

Related: 'Making a Murderer' coverage, archived stories and more

HBO's prized possession "Game of Thrones" wrapped its fifth season in June with a finale that drew more than 18 million viewers the week following the episode's airing.

"Is it possible that 'Making a Murderer' has gotten to that number? Probably not, because it's only been out for less than a month," Adalian said. "(But) it wouldn't be surprising. It wouldn't be impossible for Netflix to do that, but honestly, that's all speculation. It could just be 1,000 people in the media watching it and talking about it on Twitter."

Keeping quiet

Why doesn't Netflix talk numbers? In the traditional TV world, ratings are a tool used for selling advertising time. Netflix depends on subscription fees, not advertising dollars — which is why we're able to rip through more than 10 hours of "Making a Murderer" without commercial interruption.

"There's no business reason for us to publish ratings other than to create artificial pressure on a show to perform on a short timeframe," Netflix content chief Ted Sarandos told Variety in 2013, the same year they began putting out their own original programming.

Day 3: Defense arguments not in 'Making a Murderer'

Despite keeping quiet on their audiences, Netflix has made a lot of noise come awards season. Their first foray into original scripted series, "House of Cards," has been nominated for 33 Emmy Awards. Another of their acclaimed shows, "Orange is the New Black," has earned 16 nominations. Both were among the nominees for outstanding drama series during the most recent Emmy awards show in September.

It seems not that long ago Netflix was just a service for discs in red envelopes. But in just a few years, we're long past the point of viewing it as some upstart rival to traditional television. It's streaming service is available in 190 countries and in 21 languages.

At the start of the year, it had more than 70 million subscribers. Netflix CEO Reed Hastings recently told the Associated Press that subscribers watched 42.5 billion hours of programming in 2015 and they're now watching an average of 13 hours per week.

Attempts made

Some insight into Netflix viewership was provided by Luth Research last year, which compiled data from 2,500 subscribers using computers, tablets or smartphones. In that small sample size, they found 10.7 percent of subscribers watched at least one episode of the Netflix original series "Daredevil" in the first 11 days it was available. That amounts to about 4.4 million U.S. viewers.

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Does that sliver of information on a Marvel superhero series give us insight on the possible reach of a true crime story? Maybe. Maybe not.

"Especially given the fact that Netflix is not timeslot-dependent programming — it's not stuff that airs at one time, it's sort of always on — I just feel like it's very hard, unless Netflix releases data, for it to be worth anything," said Adalian of the bits of Netflix research that's trickled out.

Looking elsewhere

Another way to try to gauge the show's popularity is through its response online.

• Using the Twitter hashtag-tracking tool Hashtagify.me, #MakingAMurderer was in just the 10th percentile of the more than 52 million hashtags in use four weeks ago. By Monday is was nearing the 70th percentile.

• On Dec. 18, the first episode also was uploaded to YouTube (likely in hopes to entice non-Netflix subscribers to jump on board). As of Monday morning, it had more than 877,000 views.

• On Dec. 23, the official "Making a Murderer" Twitter account (@MakingAMurderer) had fewer than 4,000 followers. By Jan. 1 that number had climbed to more than 26,000 and by Monday it was beyond 77,000. The official "Making a Murderer" Facebook page is nearing 200,000 likes.

• The handling of the Avery case by law enforcement has fueled some of the response to the show, offering a little more insight. A petition on whitehouse.gov for Avery to be pardoned had nearly 130,000 signatures as of Monday. A change.org petition had amassed more than 397,000. (The attention was enough to warrant a response from the White House last week, reminding the public that the president cannot pardon those convicted of state crimes.)

Another phenomenon

Another interesting comparison can be made between "Making a Murderer" and the "Serial" podcast that had similar buzz in 2014. The true crime story of a 1999 murder of a Baltimore high school girl and the eventual conviction of her ex-boyfriend was a pop culture phenomenon, eliciting countless conversations, loads of follow-up stories, think pieces, podcasts about the podcast and even a "Saturday Night Live" spoof.

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Despite the success, the Pew Research Center reported that in January 2015 — a few weeks after the first season of "Serial" wrapped — just 17 percent of Americans listened to podcasts. That means about one in six Americans even have the podcast medium on their radar.

Compare that to Netflix, a service which more than half of American Internet users said they used to stream content, according to findings in a recent RBC Capital Markets survey.

"Serial" became the fastest podcast to reach 5 million downloads on iTunes and, since its debut in October 2014, Season 1 has exceeded more than 100 million downloads.

"Making a Murderer" and "Serial" are by no means apples to apples, but it should give a general idea of the sort of viewership numbers possible for the Netflix series.

Shane Nyman: 920-996-7223, snyman@postcrescent.com or on Twitter @shanenyman