In the absence of a gold standard, comparing and assessing the face validity of allocations from models using different need indicators is important.
We assessed three key domains of internal validity, concealment of allocation, blind adjudication of outcomes, and the inclusion of all randomised participants in the analysis according to the intention to treat principle (see supplementary appendix).
Numerical results demonstrate the validity of the allocation strategy and conclusion arrived in this study, but we do not find the similar arguments in the literature so far, for comparison with the conclusion of this study.
The validity of the proposed power allocation strategy under various channel link conditions is demonstrated by means of numerical simulations.
In the present study, the validity of the applied group allocation was confirmed by the histological examinations of endometrium biopsies because cows in group M had a higher prevalence of endometritis in the second and third postpartum estrus compared to cows in group H.
Reviewers assessed study validity and applicability by appraising concealment of allocation, blinding, handling of withdrawals, cointerventions, compliance, similarity of timing of outcome assessment, and adherence to the intention to treat principle.
Building on previous research around methodological quality of RCTs [ 4, 5], the Cochrane Collaboration recently introduced a tool designed to appraise ROB, encompassing six domains related to the internal validity of a trial: sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting, and "other" potential threats to validity [ 3].
The methodological aspects assessed in reviews most often pertained to study design, appropriateness of allocation procedures, comparability of groups, validity of assessment and attrition, but only a few reviewers examined additional aspects such as quality of implementation.
Common types of bias that affect internal validity include allocation bias, blinding, data collection methods, dropouts, etc. [37].
Furthermore, the Jadad scale contains no mention of allocation concealment, which is important in the evaluation of an RCT's internal validity.
