Luke I quite agree with your comments re. sample size, the same thoughts occurred to me when I read Henry's response. Henry, I am sorry to criticize but your comments discounting a study with 1538 because it disagrees with your personal experience (as Luke says, a sample of size of 1) comes across as somewhat arrogant. If you wish to convince others of your belief then perhaps you should provide more convincing evidence. Please take this as constructive criticism and not a personal attack. Stewart Harrison Physiotherapist UK %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%