Abstract
The presented article has a theoretical and methodological character and discusses the possibilities of using measures of effect size, including their confidence intervals, on the example of tests in education. The article is divided into three parts.
The first part describes and compares the issues of using statistical significance and measures of effect size. The text then deals with the basic measures of effect size and with the questions of their use.
In conclusion, the authors try to critically evaluate and synthesize the presented information. The authors aim to bring this issue closer to the readers so that they are able to address the issue themselves and use the mentioned analyses in their research.
The entire presentation is performed on the basis of real data.