But, the assumption has been that phone time is app time, at the expense of mobile web. I’m not sure that’s true. While yes, people are engaging with apps, I’m guessing that a good chunk of that time is actually spent on websites from inside the app.

And that comes with a special set of design challenges and considerations. How big a deal is this? Is this really a problem? Let’s take a look at some rough numbers.

Numbers Take 1: In-app Safari Stats

According to Polyvore’s stats via Google Analytics, there are 19% in-app safari vs. 81% safari views. That means at least 1 out of 5 of our mobile web sessions come from an app.

It’s nothing to sneeze at. But! That number is actually undercounting app webviews.

In the user agent, the app browser is sometimes missing or changes with each app version. I have even seen it disappear after a buggy app release. So, there’s no way that the Google Analytics in-app safari number is getting all of them.

Numbers Take 2: Social Traffic

Let’s come at the numbers a different way. Looking at Polyvore stats, there’s a 1–1 mapping of traffic source to browser, where search/referral/direct traffic use Safari, and social traffic uses in-app Safari. Pairing that with numbers from Define Media Group, it gives us 11% in-app views coming entirely from social traffic. This is probably Facebook app traffic for most of you.

Wait … that’s a smaller number than the in-app Safari counts. Why? This number is also undercounted, with wrong attributions getting dumped into direct traffic.

Numbers Take 3: Dark Social

There’s a concept called dark social, which is impossible-to-track social traffic that gets counted as direct traffic instead. For example, think about when you copy a link from Instagram. RadiumOne’s 2014 analysis estimated that it’s double known social traffic. For Polyvore, that’d be 2 × 11% social = 22% total traffic is dark social.

So, let’s guess how much of direct traffic is misattributed. Using Polyvore’s session numbers, I picked a rough lower bound of 33%, from direct traffic that is already known to be in-app browsers. And, the upper bound of 80% comes from ridiculous URLs I don’t expect anyone to type into a phone. Averaging those gives us 50%, which means half of direct traffic is dark social, or 0.5 × 39% direct = 20% total traffic is dark social.

And hey, look at that, 22% and 20% are pretty close! Close enough that I’m comfortable saying 20% of direct traffic is dark social. Roughly, of course.

Adding 20% dark social to 11% social = 31% total social, which we know directly correlates to in-app views, so …
1 out of 3 web sessions to your site are inside someone else’s app!

This is why it’s so important to design for the in-app browser. Also, yay back-of-the-napkin-wonky-math.

Stay tuned for part 2, where I ramble about how to actually design for the in-app browser.

This material was first presented at the Future of Web Design SF 2015.