As our winter semester comes to a close, it turns out students won’t be the only ones signing off for the summer. 

Many of our favourite fictional friends will also soon sign off as most TV shows air their season finales in what the entertainment industry calls “May Sweeps.” Once shows end their season, broadcast networks band together to renew or cancel every program in their lineup before the advertising presentations known as the “Upfronts” start in May.

The annual May Sweeps process often results in popular series getting renewed, less-watched shows being cancelled and a few heartbreaking surprises being left for those stuck in the middle. 

While some shows — including This Is Us and The Good Doctor — already know they’ll be back in September, the future for most others is completely up in the air, with the exception of the already-cancelled Once Upon a Time and The Mayor. 

There are numerous ways television networks measure their shows’ performances to determine whether they’re worthy of staying on the screen. Here are some reasons your favourite show may or may not be coming back later this year.

Overnight ratings

This method of measuring a show’s popularity is seemingly self-explanatory. Overnight ratings refer to the amount of people who watch a show live, as it airs. For decades, TV networks have used these numbers as their guiding light. High overnight ratings are good, low overnight ratings are a death sentence.

The method of obtaining these numbers, however, isn’t as straightforward as you may think. Nielsen, the premier data measurement company, installs measurement modems called “black boxes” in a select number of diverse households that are used to represent a country’s population. 

Out of the 118 million households in the United States — the largest exporter of television shows — that have televisions, only around 50,000 houses have these boxes measuring their viewership. Similarly, around 3,000 households in Canada have their TV habits measured to represent the 12 million households with televisions. This sampling of viewers, which is supposedly wide-ranging enough to accurately portray entire countries’ watching patterns, is then calculated to determine how much of the country watched a specific show when it aired live. 

The most important metric used to decide a show’s fate from these findings is how many people between the ages of 18 and 49 — the prime audience for advertisers — watched live. Since commercials are how shows primarily earn revenue, companies will often value this number above overall ratings.

Once the overall viewership numbers come in and 18 to 49-year old viewership is translated into a percentage of how many people in the age group with televisions watched a show, Nielsen delivers the ratings to the broadcast networks. More eyeballs watching a show means a better chance to sell the products advertised in commercial breaks, so low-rated shows are typically discarded regardless of their quality.

DVR and online viewership

A few years ago, TV networks would’ve based a show’s renewal prospects solely on how many people watch it immediately. However, as our watching habits shift, so do the methods of measuring and monetizing them.

Live TV viewership has been on the decline for years and the standards for how many people need to a show for it to be popular are constantly changing. The drop of viewers over the past decade is so drastic that Riverdale, a very popular show by today’s standards, is averaging a rating 40 per cent lower than the lowest-rated show of 2011.

This change has bolstered the importance of those who watch shows on their DVR or on official streaming sites. New metrics, like the “Live+3” or “Live+7” ratings, now measure how many people view an episode of a show within three days and a week of its airdate.

For some shows, this measurement can be their saving grace. A recent episode of Criminal Minds scored a 0.9 per cent in 18 to 49 ratings — a record low for the 13 year old show. This rating increased by 89 per cent after three-day viewership was factored in and could easily be the reason the show lives to see a 14th year.

International appeal

Another huge source of income for broadcast networks in Canada and the United States is the money they get for selling shows to other networks across the world. Sometimes, if a show is popular overseas, a network will continue producing episodes even as its homegrown popularity wanes. This strategy allows shows like Elementary and Quantico — both of which are wildly popular across Europe — remain alive despite abysmal ratings in the US.

Whether your favourite show makes it out of this TV season alive or not, we can all have some peace of mind knowing May also brings announcements of next year’s new shows. 

If none of those interest you, the new season of Game of Thrones is just a quick year-and-a-half-wait away.