Thanks Rick and Paddy for your replies.

Please excuse the rather pedantic nature of what follows but, IMHO, testing is critical, especially if we white-rat. We need to get it right.

Timing standing on one leg to "measure" PD has a number of advantages:
- it is probably valid. I have no data or reference for this*, but I would expect the true value of one's standing on one leg time, i.e. average over many runs, correlates well with one's true PDedness, as well as with wider measures of PD such as UPDRS.
- it is understandable. We all know what it means.
- it is directly comparable between people. If you achieve 67 seconds and I 7 seconds, you're doing better than me. (Contrast this with the weight you can lift, the raw value really needs moderating by body size.)
- it is hard to cheat at. We know when it's not being done properly.
- it is easy to measure. You can use a watch.
- it can be accurately measured. With a watch you should be able to time the instant of foot down to within 1 second.
- it is, effectively, free. It uses no specialist equipment.
- it is theraputic. Doing it improves balance.
- it is relevant. It relates well to the ability to walk and dress etc..
- it is, over a wide range, linear. Doubling the time indicates double the ability.

However, at least for me, it has a number of drawbacks:
- it is open ended. On a good day I could be there for 10 minutes. When I've done this test at the hospital they've stopped it at 30 seconds: pragmatic for progression purposes, but no good if I really want to know how my condition today compares with yesterday
- it's very variable: two back to back runs can vary between 1 sec and 10 minutes. Rick I note that you use the best of 5. Certainly that reduces the variability, but it increases the time required significantly.
- there is the possibility of falling.
- it is intrusive. You can't do anything else while doing this.

And, of course, it doesn't do much to measure tremor!

[Subliminal message. Wouldn't it be useful if we agreed a set of measures and used them in white rat reports. I note I failed to do this in my recent Strobe thread.]

* Just about to post when I came across this:
"Normative Values for the Unipedal Stance Test with Eyes Open and Closed"
Springer et al.
http://web.missouri.edu/~proste/tool...inger-JGPT.pdf
Journal of Geriatric Physical Therapy, Vol 30, 1.07.
Based on the references I'd estimate it was written in 2007.

It gives averages for each age group. For instance, for people (note not just PwP) aged 50-59 based on the best of 3 trials:
with eyes open 41.2 sec;
with eyes closed 8.3 sec.

John