According to wii.qj.net, this is on their website.

When people get a stroke or some injury so bad that they need to re-learn how to walk, they'll need a rehabilitative force platform to help them through the painstaking process. Problem is, lab-grade ones cost a whopping US$ 20,000. Fortunately, the much more accessible Wii Balance Board has been found to be nearly as good as those.

"We found the data to be excellent", said Ross Clark of the University of Melbourne. "I was shocked given the price: it was an extremely impressive strain gauge set-up." Clark and his colleagues were so impressed that theye even wrote a paper citing the advantages of the Balance Board over the hell-lot-pricier force platforms.

For just a hundred bucks on Amazon bundled with Wii Fit Plus, imagine how much healthcare organizations can save on those platforms.
heres the link New Scientist