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  1. Content of the SAP beyond the protocol
  2. Finalisation of the SAP before unblinding
  3. Documentation requirements for deviations from the SAP

Academy · Research Data, Analytics & AI · SAP

Statistical Analysis Plan (SAP): Scope, Finalisation Before Unblinding and Deviations

A statistical analysis plan (SAP) finalised after unblinding no longer functions as a pre-specified plan and becomes, in effect, a post-hoc rationalisation. This article examines the scope of the SAP, the significance of its timing and the requirements for a credible deviation.

Pubrica AcademyWritten by a biostatistician Reviewed bya clinical trial methodologist Published10 October 2026 Last checked10 October 2026 Reading time4 minutes Sources1 peer-reviewed

A Statistical Analysis Plan (SAP) is a document, finalised before unblinding, that sets out in technical detail how the principal features of a trial's design will be translated into a planned analysis, per ICH E9 on statistical principles for clinical trials.

Learning objectives

  • The content an SAP covers that the statistics section of a protocol typically does not.
  • The reasons finalisation before unblinding is the defining purpose of an SAP rather than a formality.
  • The requirements a deviation from the SAP must meet to remain credible.

Common misconceptions

  • “The protocol's statistics section is detailed enough that a separate SAP is redundant.” ICH E9 treats the SAP as a more technical, detailed elaboration of the protocol's principal features — covering exact definitions of analysis populations, handling of missing data, specific model specifications and planned sensitivity analyses — detail usually beyond what the protocol itself carries. The principal analyses are prespecified in the protocol, and the detailed plan is finalised and approved before treatment unblinding and before analyses that could influence analytical choices.

Content of the SAP beyond the protocol

ICH E9 describes the SAP as containing a more technical and detailed elaboration of the principal features of the analysis described in the protocol, including precise definitions of analysis populations (ITT, per-protocol), specification of how missing data will be handled, exact statistical model specifications, and any planned sensitivity or subgroup analyses1. This level of technical detail typically exceeds what the protocol's own statistics section carries.

Finalisation of the SAP before unblinding

The SAP must be finalised before the trial is unblinded, so that analytical decisions are fixed before it can be known which choices would favour a particular result. An SAP finalised or materially amended after unblinding undermines the purpose of pre-specification, however reasonable the analytical choices appear in isolation.

Documentation requirements for deviations from the SAP

Where an analysis deviates from the pre-specified SAP — because of an unanticipated data issue, for example — the deviation should be documented, dated, and explained in the final report, distinguishing pre-specified from post-hoc analyses explicitly, consistent with the broader expectation that confirmatory and exploratory analyses are clearly labelled as such.

Key points

Key points

The SAP is a more technical elaboration of the protocol's statistics, finalised before unblinding so that analytic choices are locked in before results can influence them — any deviation should be documented and explained, with pre-specified and post-hoc analyses clearly distinguished.

Practical application

Practical application

  1. The SAP should be finalised and approved before treatment unblinding. The principal analyses should be prespecified in the protocol. The detailed statistical analysis plan should be finalised and approved before treatment unblinding and before analyses that could influence analytical choices. Subsequent changes should be documented and justified. Where finalisation is scheduled before database lock, that timing is a project procedure rather than a requirement for every design.
  2. Any deviation from the SAP should be documented and dated. Any departure from the pre-specified plan should be recorded and explained in the final study report.
  3. The SAP should be maintained separately from, but consistently with, the protocol. The SAP should elaborate the statistics section of the protocol without contradicting it.

Frequently asked questions

Only before unblinding, with the amendment documented and dated; amendments after unblinding undermine the pre-specification the SAP exists to provide.

No — it is a separate, more technical document elaborating the protocol's statistics section. The principal analyses are prespecified in the protocol, and the detailed statistical analysis plan is finalised and approved before treatment unblinding and before analyses that could influence analytical choices.

References

  1. International Council for Harmonisation (ICH). E9: Statistical Principles for Clinical Trials. read 10 October 2026. View ICH E9 Guideline

Every source above is a peer-reviewed article, a publisher’s record of one, or a standard issued by the body that owns it. Each carries the date it was last read. Where a standard moves, this article is revised rather than left up with a note.

How to cite this article

Pick your referencing style and copy it. Your university or target journal may vary the punctuation — check its guide if it has one.

Pubrica Academy. (2026, October 10). Statistical Analysis Plan (SAP): Scope, Finalisation Before Unblinding and Deviations. Pubrica. https://pubrica.com/academy/abbreviations/sap-statistical-analysis-plan/

This article is written to be learned from. Cite it if you are referring to what it says; if you are using the evidence behind it, cite the sources listed above instead.

SAP finalisation check

Use before treatment unblinding.

[ ] Analysis populations defined precisely (ITT, per-protocol)
[ ] Missing-data handling specified
[ ] Statistical model specifications stated in full
[ ] SAP finalised and signed off before unblinding
[ ] Any deviation documented and dated in the final report

Pubrica AcademyWritten and maintained by Pubrica’s subject matter experts. Articles are revised when the underlying standards change, and each article states the date on which it was last reviewed.

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