In message , at 16:59:18 on Fri, 11
Jan 2013, Kai Borgolte remarked:
147. A 2011 study suggested 30 per cent of passengers take longer routes
due to the out-of-scale distances on the Tube map.

I'm very skeptical of that claim.

It may be true for the isolated case Paddington to Bond Street via
Baker Street/Notting Hill Gate: "Although the second route is
considerably slower (by about 15 per cent), some 30 per cent of
travellers chose it, Professor Guo found."
http://www.dailymail.co.uk/news/article-2000847/30-passengers-longer-routes-Londons-Tube-map-misrepresents-distances-stations.html

As there's a sidebar with nine of the other "fascinating facts" in that
article I think we can conclude it's the source of the 30% figure.

However, it's by no means clear if the 30% is an overall figure (as
suggested at the start of the article)

"Experts who have studied the network, which has been growing
since 1863 when the Metropolitan line opened, have found that as
much as 30 per cent of the network's passengers take the 'wrong'
- or longer - route between two stations."

Or simply conflated with the figure from the later 'illustration' of
Paddington to Bond St.

So we'd have to read the full study (which does seem to be more than
just a handful of trips).
--
Roland Perry