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An analysis change may sometimes be necessary, but interpretation depends partly on whether the decision preceded or followed outcome review. Keeping only the latest plan cannot explain which decisions were made using which information or why the analytical approach changed.
Define the question and assumptions
Connect plan versions, decision dates and information access. An operational correction, a changed scientific target and an outcome-informed additional analysis have different rationales. Assess consequences for primary or supportive status with appropriate expertise. Claims that a decision used blinded information should be supported by records of what was actually available, not simply by a document label.
Hypothetical study example
In a hypothetical study, the model changes after a results table is seen, but only the revised plan is retained. The team preserves the previous version and decision rationale. It explains the new analysis role rather than changing dates or history to make the method appear prospectively specified from the beginning.
Design review checks
- Record the previous and revised methods alongside the reason for the change.
- State the level of comparative information available at the decision time.
- Reconcile primary and additional analysis roles with the documented change history.
Record the decision and its limits
Accepted reporting identifies important deviations and their interpretive consequences. Not every change invalidates a study; transparent rationale, timing and robustness assessment are needed. Do not report only changes yielding favourable results. Retain an archive that lets an independent reviewer reconstruct the decision sequence rather than treating the existence of a final plan as sufficient completion evidence.
Frequently asked questions
- Is every analysis change unacceptable?
- No. Assess rationale, timing, access and consequences for interpretation.
- Can a revised plan erase the earlier version?
- Preserve previous versions and the decision history in a traceable form.