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  6. 6. Reporting Bias

6. Reporting Bias


This question investigates the likelihood that incomplete or absent reporting of some outcomes and not others occurred on the basis of the results (bias in selection of the reported results).

Signalling Questions

  • Was the trial analyzed in accordance with a pre-specified plan that was finalized before unblinded outcome data were available for analysis?
  • Is(are) the outcome measure(s) being assessed likely to have been selected from a set of additional outcome measures that were collected (e.g. scales, definitions, time points) but were not reported (i.e., cherry picking of results)?
  • Is the statistical analysis being reported likely to have been selected from multiple analyses of the data and chosen based on the results (i.e., have the statistical tests been chosen to maximize the magnitude of the effect rather than from an a priori plan)?


Selective reporting of a particular outcome measurement:

  • reporting only one or a subset of time points at which the outcome was measured;
  • use of multiple measurement instruments (e.g. pain scales) and only reporting data for the instrument with the most favourable result;
  • having multiple assessors measure an outcome domain (e.g. clinician-rated and patient-rated depression scales) and only reporting data for the measure with the most favorable result; and
  • reporting only the most favorable subscale (or a subset of subscales) for an instrument when measurements for other subscales were available.

Selective reporting of a particular statistical analysis when there is evidence that multiple analyses were done.