The Mystery Trend

This is a little case study of digging into our web stats a bit to understand a recent trend. Doing this sort of digging is pretty addictive and can, of course, throw up some interesting insights.
Recently we noticed a bit of an odd trend in our user stats on iwm.org.uk. Although direct comparisons are imperfect we're happy overall with how they've looked in the year since we swopped to the new site, with decent improvements in all the main crude metrics that might mean, well, something or other that's meant to be good. Last month we exceeded 500,000 visitor sessions for the first time. Here's how things have looked week-by-week from early May to mid-November

What with a general above-target performance, an odd summer (a big dip - thank you, Olympics!) and peaks in months that historically haven't been so prominent, the trends have been a bit of a departure from the norm so I thought I'd dig into it. It turned out that direct visits had increased noticeably from mid-September onwards - like, doubled.

Further, the growth was in the mobile segment and, more specifically, in iOS devices - equally iPhones and iPads. But why? This is weird. I mean, we're seeing the rapid growth in mobile traffic like everyone else, but whilst the numbers of iOS users overall increased by a couple of percent between May and November, direct visitors increased 4-fold just from September to November (whilst direct visits from Android are pretty much flat). Yep, that much.

To me directs from mobile means visits referred from apps, and in this case I certainly doubt that all those Apple fans - and only them - have suddenly bookmarked our site or emailed it to each other. So it's probably about referrals from apps, but which ones? There are few self-explanatory clues, either in where they arrive or in the timing. Plenty land on the home page:

our branch pages and visiting info:

(but not Duxford)

and a healthy number also land on collections record pages:

If the trend is evident for all of these it can't be from a single suddenly-popular app, right?
Predictably, our site gets healthy spikes of traffic from places like Reddit, the BBC or newspapers, which we shows up in our referrer traffic; perhaps the app equivalent of these websites is responsible for this other trend. But at first look the spikes don't seem to correlate, as for instance this graph of iOS visits from Reddit shows. I'd expect referrals from a Reddit app to be similar and is not much like the "directs" trend:

It just seems odd that there's been such growth in whatever apps are responsible in that period. We have a couple of apps of our own, of course, but again looking in detail at the pages they may link to doesn't provide an explanation. At first I suspected social media apps. Facebook & Twitter have not suddenly quadrupled in users over 8 weeks, but it seemed a plausible explanation for a rise in direct traffic to such a range of pages. Then I thought about search. Perhaps there's a newly popular search app on Apple devices? Aha, perhaps we're onto something:

So, referrals from Google drop off amongst iOS users at the same point that direct visits increase. Not being an iOS user I still have no idea of what's caused this, though I assume that there's a new appified version of Google that's being taken up rapidly. I think I'll need to do some more detailed analysis to make sense of this, but it looks like (a) the rise in directs doesn't mean an absolute rise in iOS users, and (b) our overall increase in visitors has nothing to do with this trend. This actually makes things a little worse for us because we now have less information about searches that bring traffic to us. Hmm.
I'd be interested in whether any of you lot seen a similar trend in direct traffic on iOS devices over recent months? Comments please!

PS if you found this blog post hoping to download stuff by the Mystery Trend, sorry to disappoint you. Interesting band though. More here.