Related Experiment Video
Updated: May 16, 2025

Problem-Solving Before Instruction PS-I: A Protocol for Assessment and Intervention in Students with Different Abilities
Published on: September 11, 2021
Effect sizes for experimental research
1Department of Statistics and Data Science, Northwestern University, Evanston, Illinois, USA.
Abstract:
Good scientific practice requires that the reporting of the statistical analysis of experiments should include estimates of effect size as well as the results of tests of statistical significance. Good statistical practice requires that effect size estimates be reported along with some indication of their statistical uncertainty, such as a standard error. This article provides a review of effect sizes for experimental research, including expressions for the standard error of each effect size. It focuses on effect sizes for experiments with treatments having a single degree of freedom but also includes effect sizes for treatments with multiple degrees of freedom having either fixed or random effects.
Related Concept Videos
Statistical Significance
Experimental Designs
What is an Experiment?
Comparing Experimental Results: Student's t-Test
Accuracy and Errors in Hypothesis Testing
In hypothesis testing, the probability of making a Type I error, denoted as α, is commonly set at 0.05. This significance level indicates a 5%...
Study Design in Statistics
Does aspirin reduce the risk of heart attacks? Is one brand of fertilizer more effective at growing roses than another? Is fatigue as dangerous to a driver as the influence of alcohol? Questions like these are answered using randomized experiments with proper...

