We notice that the series solutions converge rapidly; the absolute error was obtained with only a few perturbative terms, so we say that a good approximation has been achieved, the validity range applies to the entire domain of equation (49) and there is no restriction to a smaller domain.
In placebo surgery studies, in which participants are placed at increased risk to achieve the scientific validity provided by blinding, it is imperative that the blind be maintained, and maintainable, to justify putting subjects at risk to achieve it.
First, to achieve the required validity, most instruments were correlated with a VAS or alternative intensity scale filled in by a proxy (mostly nurses).
Under the IACCV approach, some of the response burden from the participants can be alleviated by using experts; thus fewer participants are needed to achieve the desired validity evidence in developing instruments.
The RCT study design relies on the exercise of a range of controls to minimise bias, and this is done in order to achieve the internal validity that is seen as a scientific gold standard.
Overall, a PRO validation needs to achieve the standards of validity and reliability [ 2].
To achieve the level of validity required for clinical trials, researchers should consider additional strategies to assure the validity of the data.
The Malay version IFSAC has achieved the content validity through translational process and expert review.
The German version of the PRU questionnaire was translated and back-translated according to guidelines for cultural adaptation in order to achieve the highest possible content validity [ 13].
