moondaughter,

There are two variables:
- dominant hand (the one you write with);
- worst affected by PD hand.

If we simplify the situation, by making it binary, that gives four types of persons: LL, LR, RL, RR.

I'm LR, left hand dominant, right hand most affected by PD. (But strangely my tremor which started in my right hand is now worst in my left hand).

I can only remember one time in the hundreds of times that I've done this test that my right hand score was better than my left hand score. But, notice that by my being LR both components are in favour of the left hand. I would expect something similar with RL people. However, where the two components have opposing affects on the scores, LL and RR, I would expect the crossover of scores to be more common.

In interpreting the results we must also take into account the noise in the data. If you take the test again immediately after taking it once, you would expect the results to be identical, because nothing in your condition is likely to be changed in that short period of time. But, in practice, you will find a difference that is just noise.

John