Yes, a handwriting expert has analysed Elizabeth I's signature and her general handwriting and you can read an article on this at http://www.handwriting.org/archives/98may_01.html
Of her elaborate signature taken from the death warrant of Robert Devereux, Earl of Essex, handwriting expert, Marion Rayner, says:-
"Sample C bears the famous signature produced in 1601 on the warrant for the execution of the Earl of Essex, two years before the Queen's death. The signature by this time may have been produced more by rote than as a personal signature, having become one of her royal duties, with her evident sense of position and responsibility being maintained despite the obvious lack of any ‘joie d’vivre’.
Careful observation reveals that the formation of the signature was with a slow slightly uneven pressure, indicating the effort taken and the slowly ebbing energy levels, perhaps caused as much by the emotional effect of Essex's devastating betrayal as by any health problem. In this signature we see an upright slant, which again compares with the right slanted writing to indicate her public position compared with the inner woman."