(No mention of ME/CFS specifically) http://blogs.lse.ac.uk/impactofsoci...gistered-reports-countering-publication-bias/ So one is likely generally talking about observational data cf. randomised controlled trials. There has been a move towards registering protocols for certain types of scientific work in medicine e.g. randomised controlled trials and more recently meta-analyses/systematic reviews. However such practices are much less common with the rest of science incl. medical/biomedical research that isn't testing an intervention.