The article focuses on the concept of sample size calculation or power analysis in surgical randomized controlled trials (RCTs) for the application of evidence-based medicines. It mentions that a priori sample size calculation can reduce the risk of underpowered (false-negative) results. It also ...
Below you will find descriptions and links to 16 different statistics calculators that are related to the free a-priori sample size calculator for student t-tests. The related calculators have been organized into categories in order to make your life a bit easier. ...
This calculator will compute the sample size required for a study that uses a structural equation model (SEM), given the number of observed and latent variables in the model, the anticipated effect size, and the desired probability and statistical power
In contrast, a sample size can be estimated statistically based on previous studies as a priori. For instance, the value of standard deviation, standardized mean difference, statistical power, and effect size based on previous studies can be used to determine the sample sizes [15,16,17,18,19,...
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Based on these parameters, the sample size required was 25 patients in each group. To determine the error of method, RMS calculation was repeated 7 days after the first measurement was performed on 15 randomly selected casts, by the same observer (FR) and by a second observer (GC) - two...
Down syndrome (DS), the genetic condition caused by trisomy 21, is characterized by variable cognitive impairment, immune dysregulation, dysmorphogenesis and increased prevalence of diverse co-occurring conditions. The mechanisms by which trisomy 21 causes these effects remain largely unknown. We demonstr...
To describe the distribution of sample sizes, the mean, median, interquartile range and range were calculated. We assessed whether sample size justification was provided. The justification could be through a formal sample size calculation or narratively to explain the rationale for the sample size....
Reference for Citing the Online Calculator Soper, D.S. (2025). A-priori Sample Size Calculator for Multiple Regression [Software]. Available from https://www.danielsoper.com/statcalc References from the Scientific Literature Abramowitz, M. and Stegun, I.A., eds. (1965). Handbook of Mathemati...
Below you will find descriptions and details for the 9 formulas that are used to compute a-priori sample size values for multiple regression models. Beta function: Cohen's f2effect size for an F-test: whereR2is the squared multiple correlation. ...