I measure Instant Articles with Google Analytics for quiet a while now and doubt the results of some of the metrics recorded.
For instant articles the average time on page is 00:03:30 where normal mobile traffic from facebook is only about 00:01:00. Given that instant articles are short and simple that strikes me as to high. Also bounce rate is about 90% which leaves a remainder of 10% to calculate the average time on page; rather unreliable.
I also queried facebooks aggregated Instant Articles API and the average time is very different with about 00:01:20.
Did you experience similar results? Do you have any explanation for the stated data or an alternative idea on how to measure performance reliably and comparsion with regular mobile Facebook traffic in mind?
PS: All information are backed by data from round about half a year.