The Physics of App Friction

In a previous life, I was founder and CTO of Havok, a company that develops special effects simulation software for games and movies. One of the many challenges that Havok faced in the earlier days was the robust and efficient simulation of friction - something we take for granted in our everyday lives, but that turns out to be surprisingly difficult to accurately (or even plausibly) simulate in real-time. 

When modelling friction (don't worry, I promise this relevant!), we of course have to remember that different materials have differing coefficients of friction - sandpaper has a high friction coefficient and melting ice has a very low coefficient. And to make matters a little more complex, there are 2 such coefficients: the coefficient of dynamic friction (describing the stickiness of objects in motion) and the coefficient of static friction (the stickiness between objects at rest).

The classic way to think about this is the brick on a plank example; a brick is placed mid-way along a plank of wood, and one end of the plank is slowly lifted. As the end rises, the static friction between the plank and brick prevent the brick from sliding, until eventually an angle is reached where the gravitational force acting on the brick is greater that the 'static friction' and the brick begins to slide. At this point, dynamic friction kicks in, and the speed of the slide is governed by the gravitational force acting on the brick, and the dynamic friction force which is impeding the motion and acting in the opposite direction of the motion.

If you slowly lower the plank again, the brick doesn’t immediately stop, but starts to slow down, until eventually you reach a point where the plank is lowered such that the dynamic friction force counteracts the gravitational force, and the brick comes to rest again. This is because the coefficient of dynamic friction is normally less that the coefficient of static friction. Intuitively, it takes more effort to get an object to start sliding than it does to bring it to rest again.

App Static Friction

So what does all this have to to with apps and mobile marketing automation you might ask?

Well, these principles sort of apply in apps also, and they make a nice analogy (as well as a good excuse to dust off some of my physics history). Think of your user acquisition process as one similar to that of static friction. You have a friction force you need to overcome before you can achieve movement at all; by analogy you have to overcome the friction of the app install before you can engage with your user. You need to find the user, somehow communicate the value of your app (through advertising, social media, reviews, blogs, communities etc.), then get them to engage with the app store, find your app and install it. That’s quite the set of opposing forces - and so the force required to overcome these and get your app installed is going to be large.  

The really great news is that the force required has recently just dropped, for free apps on iOS. Apple, with iOS 8.3, have allowed the removal of the password request when downloading apps that are free. That’s pretty huge. We know from other forms of password “walls” that there is always a dropoff when presenting users with the requirement to fill out any type of form. But the road to installing the app is already quite cumbersome:

  • View Ad or relevant piece of editorial content with link to app, or search for the app or related keywords on the app-store.
  • Click link and get redirected to the app-store page for the app, or the search results page.
  • Click get followed by install after viewing the app store page for the app, verifying it’s what you’re expecting to see.
  • Input password (hopefully you can remember it!)
  • Download starts.  Quit the app-store and later navigate to the screen with next available app slot (or click open from within the app store, if you’ve nothing better to do in the interim).
  • Wait for download to start, then launch app.

That’s quite a few opportunities for your customer to lose interest or time.  Removing the password check for those free apps is a great boost to this installation process - now everything is single clicks and swipes only.

App Dynamic Friction

Good news!  Your app has been installed.  You’ve achieved a force greater than the static friction force, and now your user is engaging with the app.  Now you are in motion. And the job at this point is to keep the user “in motion”, fully engaged with the app, educating them in the benefit to them in continuing to use the app.

The coefficient of dynamic friction determines how 'frictional' this experience is (I’m not going to use the term “sticky” in this context, because we use the opposite meaning in normal circumstances - hey, it’s not a perfect analogy!) By placing barriers in the way of the user’s progress to learning the value of the app, we increase the friction, slowing the user down, and ultimately are in danger of them stopping altogether.   At this point, the forward momentum we achieved with installation has completely been lost due to the friction of the on-boarding process. There are so many things that contribute to this friction including:

  • Slow app startup times.  There are great results from the web which indicate low tolerances for slow load times.
  • Immediate requests for permissions to send push notifications or allow access to the location of the user. Without context, these requests instil a distrust in the app and are frequently rejected.
  • Immediate registration requests or requests for emails; in both cases, you’re asking the user to opt-in to the sharing of personal data, and increasingly consumers are more aware that this is not something to be taken lightly. Make sure you provide fully transparent data privacy policies, and tell them exactly why they should be registering in the first place.  Better still, wait until they are already engaged with the app.
  • Confusing placement of Advertising: unless you are careful about ensuring your advertising is contextual, relevant, thoughtfully integrated into the app experience and thus anticipated by the user, ads are generally going to be viewed as negative by the user.
  • Unhelpful onboarding tutorials or help systems.  It’s really important to test these and determine the flows that best propel your users through the early stages of engagement with your app.

Your goal is to avoid slowing the user down to the point of stopping, and removing your app. It’s easier to keep the user engaged than it is to re-engage that user from the start. Make full use of the opportunity you have in the first few minutes and hours of app usage to really drive home how great your app is. Adapt to different types of users quickly, and make sure you deliver relevant and engaging experiences to all your important user segments.

Minimize your app’s TTV (Time to Value) for your users by decreasing your app’s friction!