The Copenhagen team noted that the real impact of the probiotics may have been masked by small sample sizes and the use of different strains of bacteria and variations in participants' diets, among other factors.
Medical research is plagued by small sample sizes and inconsistent data collection.
The quality of most studies was limited by small sample sizes and cross-sectional designs.
Conclusions were limited by small sample sizes, homogeneity of sample population, and reliance on self-report.
Most publications were limited by small sample sizes, lack of control conditions, and lack of randomization.
The scientific literature on this topic is limited to anecdotal reports or studies plagued by small sample sizes.
Yet many of these studies are limited by small sample sizes and/or marked variation in reported outcomes.
The existing literature is limited by small sample sizes, lack of appropriate controls and lack of longitudinal data.
Variability in study results may partially be explained by small sample sizes resulting in limited statistical power, clinical heterogeneity between patient samples, and methodological differences between studies.
Studies were limited in their ability to establish a causal relationship by their design, by biases, and in many cases, by small sample sizes.
Although interest in ADHD pharmacogenomics is encouraging, preliminary studies have been limited by small sample sizes, inconsistent research designs, retrospective reports, and a focus on symptom response.
