Hi.<br/>What does "casual linkage" mean in:<br/>"Convincing evidence of causal linkages remains elusive"(Retrieved from:<a href="http://focus.psychiatryonline.org/article.aspx?Volume=2&page=558&journalID=21"><a href='http://focus.psychiatryonline.org/article.aspx?Volume=2&page=558&journalID=21' target='_blank' rel='nofollow'>http://focus.psychiatryonline.org/article.aspx?Volume=2&page=558&journalID=21</a> </a>)?