We now have 38 replies. (See attachment for an up to date graphic.)

My thanks go to all the new respondants and to Conductor71 for promoting the survey - this has led to many more replies.

Soccertese,

You write:
"my point is you can't verify any of your data since it's entered anonymously, it will likely be highly subjective and your sample sizes will be too small to show any significant differences"

(I want to keep the focus of this thread on handedness, so I'll reply to your other points in the "What can we do next?" thread.)

You're right about the inability to verify the data. The design decision I had to make was: do we use a more rigourous approach, which would probably mean that far fewer people would reply, or do we go for a more open approach which would encouage more replies? In this case, I went openness because I think the data is likely to be OK. I would, however, be more worried if the survey involved commercial interests.

In this case, I don't agree with you that the data is "highly subjective". A possible exception is the accuracy of the diagnosis date. My concern here is not that PwP get the date wrong (it's the sort of thing you don't forget) but, rather, the timing of the doctor's decision to label the condition "PD" is flexible.

Regarding sample sizes, the sample is already big enough to make some weak statistically significant statements. However, more data would be welcome, especially to overcome the a posterori effect discussed in an earlier post.

GerryW,
On the latest figures: of the right handed men there are 11 with first symptoms on the right and only you with first symptoms on the left. Interestingly, your diagnosis was, as far as this survey is concerned, very late. See attachment. So, a claim that the effect is limited to early onset men would stand. We need more data.

John

Attached Images

handednesstableau.png (7.0 KB, 75 views)