Statistical power of a test – an analysis of a test’s power, its role in the research methodology and the interpretation of (non-)significance in a low- (high-) powered test

Lilianna Jarmakowska-Kostrzanowska

Nicolaus Copernicus University in Toruń


This study has two main aims – to present the statistical power of a test and to discuss the main problems in analyses of a test’s power with the use of a new-old tool. The applied tool is new because it marks a recent addition to a researcher’s standard toolbox, but it is old because has been long recognized in statistics. The technical aspects of a power analysis in relation to the p-value were also discussed. 

The power analysis and statistical significance are concepts that originate from two different approaches to null hypothesis statistical testing (NHST). The lack of conformity between different approaches to the NHST paradigm creates problems in the interpretation of test results.

The required sample size can be determined in a power analysis, but the results of a power test are not easy to interpret. There are no clear rules for interpreting a statistically non-significant result in a high-powered test or a significant result in a low-powered test. A test’s power does not confirm the statistically significant result, nor does it disprove the null hypothesis when the result is not statistically significant.

Słowa kluczowe:

statistical significance, p-value, power analysis, power of a test

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Cited By /

Jarmakowska-Kostrzanowska, L. (2021). Statistical power of a test – an analysis of a test’s power, its role in the research methodology and the interpretation of (non-)significance in a low- (high-) powered test . Przegląd Psychologiczny, 64(4), 177–193.

Lilianna Jarmakowska-Kostrzanowska 
Nicolaus Copernicus University in Toruń


Prawa autorskie (c) 2022 Przegląd Psychologiczny

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