Reader Comments (4)

Post a new comment on this article

• 0 Responses
  10 Aug 2012
  21:23 GMT
  Most Recent
  Publisher's Note: 30 years Posted by adduct on 10 Aug 2012 at 21:23 GMT
• 0 Responses
  10 Aug 2012
  21:21 GMT
  Most Recent
  Publisher's Note: 30 years Posted by adduct on 10 Aug 2012 at 21:21 GMT
• 0 Responses
  28 Apr 2012
  23:39 GMT
  Most Recent
  Publisher's Note: Five waves, not six Posted by adduct on 28 Apr 2012 at 23:39 GMT
• 0 Responses
  28 Apr 2012
  23:37 GMT
  Most Recent
  Publisher's Note: Error in fixed-effects model Posted by adduct on 28 Apr 2012 at 23:37 GMT