There were many potential methodological biases that could undermine this study.
However, the authors found many methodological problems, publication bias, and considerable variation in valerian doses and preparations, and treatment duration that led them to conclude the need for further studies.
A review of the studies of behavioral treatment of headache [67] reports a 35 55% improvement but also emphasizes many methodological imperfections, including selection bias, credibility of the control procedure, and lack of reproducibility of the results.
The included studies were generally rated at risk of bias, as many methodological criteria were rated as 'unclear' because of a lack of information.
The principles of EBM place the RCT as the 'gold' standard since in study design since many methodological issues including selection, performance, attrition and detection biases may be controlled.
There were few patients and methodological biases were numerous.
However, the evaluated RCTs had many methodological shortcomings.
Most of these studies were observational, with a small number of patients and methodological biases [116 120].
However, most of these studies were observational, with a small number of patients and methodological biases.
Over the years, experienced palaeographers have devised many methodological approaches to writer identification.
