| Study author contacted | Study author replied | Study author asked for additional information | Study author provided data | |
| Barczynski 2012 | 04/04/2014 | 05/04/2014 | Yes | Yes |
| Witte 2000 | 04/04/2014 | Did not reply | Yes | No |
| Jarhult 2005 | 24/11/2012 | 25/11/2012 | Yes | Yes |
| Chi 2005 | 04/04/2014 | Did not reply | Yes | No |
| Muller 2001 | 04/04/2014 | Did not reply | Yes | No |
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