Statistical analysis: sample size and power estimations

Sample size estimation and statistical power analyses

The concept of sample size and statistical power estimation is now something that Optometrists that want to perform research, whether it be in practice or in an academic institution, cannot simply hide away from. Ethics committees, journal editors and grant awarding bodies are now increasingly requesting that all research be backed up with sample size and statistical power estimation in order t...

Sample Size and Statistical Power Calculation in Genetic Association Studies

A sample size with sufficient statistical power is critical to the success of genetic association studies to detect causal genes of human complex diseases. Genome-wide association studies require much larger sample sizes to achieve an adequate statistical power. We estimated the statistical power with increasing numbers of markers analyzed and compared the sample sizes that were required in cas...

Sample Size Determination and Statistical Power Analysis in PLS Using R: An Annotated Tutorial

How Many Are Enough? Statistical Power Analysis and Sample Size Estimation in Clinical Research

One of the most common questions asked of statisticians is, “How many are enough?” The answer to that question, unfortunately, is complex, and only part of it can be answered by the statistician. This is because power calculation is part mathematical calculation and part judgment call. The former requires knowledge about population characteristics; the latter requires choices about tolerable er...

Sample Size Issues and Power

1 USP 656 Multilevel Regression Winter 2013 Sample Size Issues and Power There are two sample size issues to be concerned about. One issue has to do with the minimum number of cases needed for using multilevel regression to avoid biases. The second issue concerns sufficient statistical power needed for obtaining significance. Generally, having more groups is more important than having more case...