My goal is to try, as best I can, to explain the complicated parts of the entertainment biz, trying to walk readers through what I’m doing and how I’m doing it. Unfortunately, even when I’ve tried to simplify things, I’ve gotten comments that my articles are pretty dense. That’s what happens when you don’t have an editor.
With that preamble, today’s article is math-y.
This is about as math-y as I can get. I’ll be slinging terms like linear programming and mean absolute percentage error. To help out, I’m going to start with a BLUF (bottom line up front) so you can read my findings even if you don’t want to read my process to learn how I pulled it off.
Today is the “Bass Diffusion Model” in action. In layman’s terms, the Bass Diffusion Model is a way to calculate a “total addressable market” (TAM or “market size” in non-jargon terms) for various new products or innovations. As the headline suggests, today we’re turning our gaze towards Netflix as a stand-in for the streaming world.
BLUF – Netflix’s Market Size in the US is closer to 70 million than 90 million
When you apply the Bass Diffusion Model to Netflix’s US operations, the model which fits best has a market size in the United States of around 70-72 million subscribers. In other words, a saturated US market is much closer to the low end of Netflix’s projected outcome (60 million) than the high end (90 million).
The Bass Diffusion model fits the data pretty well. My average “error” fitting the Bass Model to Netflix is 1 million for streaming only and 600K for all subscribers.
That said, applying the Bass model to Netflix isn’t perfect. First, Netflix transitioned from a DVD company to a streaming company, which is arguably two different product innovations. Second, Netflix isn’t alone in the streaming world, and we only have current Netflix subscribers in any period, and don’t know how many folks are still streaming, but no longer Netflix subscribers. Third, this is a US only model. In the future, I plan to apply the projections to the international markets (which has its own problems) and for all streamers.
The Origin Story – Seeing Bass Diffusion Applied in the early 2010s.
Going to b-school during the Qwikster debacle of 2013 made for interesting class discussions. Overnight, Netflix became a laughing stock. Yet, even with that debacle the year before, they had kept adding streaming customers. They were the growth story already—23%!—leading some early analysts to throw out huge potential market sizes. How long would this double digit growth continue for?
That’s when my professor—a marketing professor, naturally—trotted out the Bass Diffusion Model. We’d all learned this model in marketing the year before; I’d never considered applying it here. He did, and out popped a total market size: about 60 million US subscribers. The model fit really well.
That 60 million has stuck in my head and influenced my thinking ever since. It’s why I launched this series and why I kept my annual subscriber projections a bit lower than most observers last January. Seriously, look at this chart I made back for an article on Hulu at Decider. Bass doesn’t leap off as strongly as it did for Fortnite, but you can see it for Netflix and especially see it for Hulu.
Frankly, because of that one application, the 60 million subscribers point in the US felt like the point where we’d see Netflix slow down. Then, in Q2 of this year…that reality finally happened.
The good news for Netflix is the last few years have had better subscriber growth for Netflix than that old Bass model. (For those keeping score, my projection last year was probably too low.) The bad news? Well, 90 million subscribers is looking MUCH harder to reach. But instead of relying on old estimates, today is about making new ones.
The Task – Forecast Netflix Subscriber Growth in the United States
Just to be clear, my goal today is to apply the Bass Diffusion Model to Netflix’s US subscriber count. Why US only? Well, it has a few more data points which will make it a bit more accurate. More over, the recent slow down point gives me a bit more confidence that we’re seeing the inflection, which I’m not sure we’ve seen internationally yet.
I’ll be building two models, though, because Netflix has actually had two products: the DVD delivery and streaming video. Unfortunately, Netflix has been a bit tricky when it releases subscriber counts, which means I needed to make some assumptions. Let’s explain those.
The Data – Netflix Subscriber Counts Over Time
To really make the Bass model work, I needed to do a lot of cleaning of my Netflix subscriber data to make sure everything I was calculating was apples-to-apples. Wait, doesn’t Netflix provide this? They do, every year. Here’s a Statista table summarizing that. Can’t we just use that?
Unfortunately, it’s a bit unreliable. When I use data, I pull it myself so I can vet it. For example, with those Statista numbers, are those numbers paid subscribers or free? Streaming only? Or all subscribers? Many tables and charts for Netflix actually mix up those categories in the same chart.
In fact, even in my chart above—the one for Decider—I did a bit of that.
So I updated all my Netflix subscriber numbers, calculating streaming and all subscribers for Netflix from the beginning of time. This took me SO long—and I had some insights into Netflix’s history from it—that I’m going to write it up as its own, probably too-in-the-weeds, article. In the meantime, just know these colors are the six different ways Netflix has revealed subscribers to investors: