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	Effektestimering	Effektstorleksanalys
Ämnesområde	Statistik	Statistik
Familj	Hypothesis test	Hypothesis test
Ursprungsår	1969 (1st ed.); 1988 (seminal 2nd ed.)	1969 (first edition); 1988 (definitive second edition)
Upphovsperson	Jacob Cohen	Jacob Cohen
Typ	Sample size and power planning	Standardized magnitude estimation
Ursprungskälla	Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences (2nd ed.). Lawrence Erlbaum Associates. ISBN: 978-0805802832	Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences (2nd ed.). Lawrence Erlbaum Associates. ISBN: 978-0805802832
Alias	sample size calculation, power calculation, sensitivity analysis, a priori power analysis	effect magnitude estimation, standardized effect measure, practical significance analysis, ES analysis
Närliggande	5	4
Sammanfattning	Power analysis is a planning and evaluation technique that quantifies the probability of detecting a real effect of a given magnitude at a chosen significance level. It links four quantities — sample size, effect size, significance level (alpha), and statistical power (1 minus beta) — so that researchers can determine the sample size needed before data collection or evaluate the sensitivity of a completed study.	Effect size analysis quantifies the practical magnitude of a statistical result independently of sample size. Rather than asking only whether a difference or relationship is statistically significant, it asks how large it is, using standardized indices such as Cohen's d, eta-squared, omega-squared, or Pearson's r that allow direct comparison across studies and populations.