Table 1 Common issues in pre-specifying statistical analysis approaches in clinical trial protocols

Omitting an aspect of the analysis approach

Investigators could run multiple analyses, and selectively report the most favourable

Analysis population:

Analysis model:

Covariates:

Missing data:

27-47%

11-20%

27%

66-77%

Insufficient detail around an aspect of the analysis approach

Investigators could run multiple analyses, and selectively report the most favourable

Analysis population:

Analysis model:

Covariates:

Missing data:

64%

42%

23%

17%^b

Analysis approach allows some aspects of the final analysis to be subjectively chosen based on trial data

Investigators could run multiple analyses, and selectively report the most favourable

Analysis model:

Covariates:

19%

8%

Multiple analysis approaches specified, without one being identified as the primary

Investigators could selectively report the most favourable result, or to elevate its importance compared to less favourable results.

Analysis population:

Analysis model:

Covariates:

Missing data:

11%

11%

9%

2%