According to mobile application performance management company Crittercism, Apple's latest iOS 8 release is seeing crash rates which are 78 percent higher than those seen on iOS 7.
The average crash rate across all devices is 3.56 percent, but on breaking down the numbers further Crittercism discovered that older devices are crashing much more than the new iPhone 6 and iPhone 6 Plus devices, with the average for the iPhone 4, 4s, 5 and 5s being 3.57 percent, compared to 2.63 percent for the iPhone 6 and 2.11 percent for the iPhone 6 Plus.
The average iOS 7 crash rate as seen by Crittercism is 2.0 percent.
Crashes will be a result of both bugs in iOS 8 and buggy apps, and so over time as iOS and app updates are released, this figure should do down. It's possible too that older handsets are running old apps that either haven't been updated, either because the user hasn't applied the update or because the app has been abandoned by the developer and won't see any further updates.