An introduction to power and sample size estimation
TL;DR: The importance of power and sample size estimation for study design and analysis and the role of meta-analysis in this work is illustrated.
Abstract: Previous evidence suggests different cortical areas naturally oscillate at distinct frequencies, reflecting tuning properties of each region. The concurrent use of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) has been used to perturb cortical regions, resulting in an observed post-stimulation response that is maximal at the natural frequency of that region. However, little is known about the spatial extent of TMS-induced activation differences in cortical regions when comparing resting state (passive) versus active task performance. Here, we employed TMS-EEG to directly perturb three cortical areas in the right hemisphere while measuring the resultant changes in maximal evoked frequency in healthy human subjects during a resting state (N=12) and during an active sensorimotor task (N=12). Our results revealed that the brain engages a higher dominant frequency mode when actively engaged in a task, such that the frequency evoked during a task is consistently higher across cortical regions, regardless of the region stimulated. These findings suggest that a distinct characteristic of active performance versus resting state is a higher state of natural cortical frequencies.
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TL;DR: Few methods of sample size calculations for animal studies are suggested on the basis of review of literature done by us and these methods may lead to unnecessary wastage of resources and ethical issues.
Abstract: Calculation of sample size is one of the important component of design of any research including animal studies. If a researcher select less number of animals it may lead to missing of any significant difference even if it exist in population and if more number of animals selected then it may lead to unnecessary wastage of resources and may lead to ethical issues. In this article, on the basis of review of literature done by us we suggested few methods of sample size calculations for animal studies.
1,029 citations
Cites methods from "An introduction to power and sample..."
...For simple statistical tests such as Students t‐test or Chi‐square test, manual calculation based on formula can be carried out [Appendix], but for complex tests like ANOVA or non‐parametric tests help of statistician or use of software is needed[2,4] • Expected attrition or death of animals: Final sample size should be adjusted for expected attrition....
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TL;DR: This review provided a conceptual framework of sample size calculations in the studies of diagnostic test accuracy in various conditions and test outcomes to help clinicians when designing diagnostic test studies that an adequate sample size is chosen based on statistical principles in order to guarantee the reliability of study.
556 citations
TL;DR: Compared with the BQ, STOP, and ESS, the SBQ is a more accurate tool for detecting mild, moderate, and severe OSA and should be used for the early diagnosis of OSA in clinical settings, particularly in resource-poor countries and sleep clinics where PSG is unavailable.
408 citations
TL;DR: It is demonstrated that cancer can be non-invasively detected up to four years before current standard of care and patients whose disease is diagnosed in its early stages have better outcomes.
Abstract: Early detection has the potential to reduce cancer mortality, but an effective screening test must demonstrate asymptomatic cancer detection years before conventional diagnosis in a longitudinal study. In the Taizhou Longitudinal Study (TZL), 123,115 healthy subjects provided plasma samples for long-term storage and were then monitored for cancer occurrence. Here we report the preliminary results of PanSeer, a noninvasive blood test based on circulating tumor DNA methylation, on TZL plasma samples from 605 asymptomatic individuals, 191 of whom were later diagnosed with stomach, esophageal, colorectal, lung or liver cancer within four years of blood draw. We also assay plasma samples from an additional 223 cancer patients, plus 200 primary tumor and normal tissues. We show that PanSeer detects five common types of cancer in 88% (95% CI: 80–93%) of post-diagnosis patients with a specificity of 96% (95% CI: 93–98%), We also demonstrate that PanSeer detects cancer in 95% (95% CI: 89–98%) of asymptomatic individuals who were later diagnosed, though future longitudinal studies are required to confirm this result. These results demonstrate that cancer can be non-invasively detected up to four years before current standard of care. Patients whose disease is diagnosed in its early stages have better outcomes. In this study, the authors develop a non invasive blood test based on circulating tumor DNA methylation that can potentially detect cancer occurrence even in asymptomatic patients.
295 citations
TL;DR: General recommendations for future pre-clinical studies that allow better standardization of study protocols will allow better comparison and contrast of newly developed bone substitute biomaterials that help further progress in the field of biomaterial science.
206 citations
References
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TL;DR: A diagnostic algorithm based on a simple model and a non-enzyme-linked immunosorbent d-dimer assay was used in patients presenting to emergency departments with suspected pulmonary embolism to demonstrate the safety of excluding the diagnosis of pulmonary emblism in an emergency department using diagnostic algorithms based on pretest probability and d-Dimer assay results.
Abstract: Managing patients for suspected pulmonary embolism on the basis of pretest probability and D-dimer test result is safe and decreases the need for diagnostic imaging.
1,285 citations
TL;DR: The Canadian CT Head Rule is developed, a highly sensitive clinical decision rule for use of CT that has the potential to significantly standardise and improve the emergency management of patients with minor head injury.
1,281 citations
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05 Dec 2015
TL;DR: Diagnosis, Epidemiology and Aetiology of diabetes Biochemistry and Pathophysiology of Diabetes Management of Diabetes Monitoring of Therapy Special Problems in Management Acute Disturbances of Diabetes Chronic Complications of Diabetes Diabetes and Public Health.
Abstract: Diagnosis, Epidemiology and Aetiology of Diabetes Biochemistry and Pathophysiology of Diabetes Management of Diabetes Monitoring of Therapy Special Problems in Management Acute Disturbances of Diabetes Chronic Complications of Diabetes Diabetes and Public Health.
637 citations
TL;DR: The simple methods and tables in this paper guide the researcher when deciding how many subjects to sample in a study designed to estimate both the sensitivity and the specificity of a diagnostic test, given a specified precision and estimated disease prevalence.
Abstract: Careful consideration of statistical issues related to the choice of a sample size is critical for achieving meaningful results in research studies designed to evaluate diagnostic tests. When assessing the ability of a diagnostic test to screen for disease, the parameters sensitivity, specificity, and predictive values are of interest. Study sample size requirements can be calculated based on a clinically acceptable degree of precision, the hypothesized values of sensitivity and specificity, and the estimated prevalence of disease in the target population. The simple methods and tables in this paper guide the researcher when deciding how many subjects to sample in a study designed to estimate both the sensitivity and the specificity of a diagnostic test, given a specified precision and estimated disease prevalence.
502 citations
312 citations