There is no measure. The path to enlightenment is full of ups
and downs through countless lives. People approaching enlightenment
demnstrate compliance with the Eighfold Path without forcing
themselves. Even people wo strive mightliy towards perfecton may be
saying to themselves "Ain't I great at how I'm doing this" but this
may lead them further from Nirvana than towards it.
I'd just like to add, in some schools of Tibetan Buddhism there
are teachings, some contained in widely published texts, which set
out the state of one's development set against the goal of full
liberation. I'm not a student of Lam Rim so can't comment on this
system but take a look at some of the work of Gampopa or Asanga;
you will see some clear pointers as to where any being may be on
the path. Some of the esoteric transmissions are hidden, in that
their full meaning may be obscured from people not at the
appropraite level of development but many of the signposts are
there in black and white.