What is the usual amount of loop closure error

[Dr Footleg]

I am fairly new to cave surveying in practice, and am trying to plot up a 
large cave system which contains much historical data plus some new data 
from my own trips. I have found some loops closures are significantly out, 
but have no idea what would be the normal expected amount of error. In other 
words, when should I suspect that there are errors in the survey data itself 
rather than just normal error in the instrument readings?

_________________________________________________________________
The new Windows Live Toolbar helps you guard against viruses 
http://toolbar.live.com/?mkt=en-gb