Surface mail version
A single standard letter, amended as necessary by the reviewer, containing
- a short introduction to the review being undertaken
- a request for data or pieces of information which are missing
An example for this letter appears here.
This letter should be sent by surface mail to the postal address of the investigator.
If they receive no reply, the reviewer should wait twelve weeks after sending the letter before attempting to contact the investigator again. After this period the reviewer may proceed in any way they feel appropriate.
This intervention is intended to replicate the usual approach taken by Cochrane reviewers. However, we do not wish to hinder any attempts to obtain important information that are used as standard by individual reviewers.
Email version
As surface mail, but sent by email. The observation time for email interventions is twelve weeks. If the investigator responds, the reviewer may enter into email, or other, correspondence with the investigator in order to retrieve the missing information by the most convenient means. If the email is unsuccessful (for example, is returned because the email address no longer exists) then the reviewer should immediately initiate the control arm using surface mail (unless the Steering group has received notification prior to randomisation that this action will not be taken, in which case the outcome for this investigator will be 'failure to contact'.)
