השוואת שיטות

	עוצמה סטטיסטית וגודל מדגם	ערך p ומשמעות סטטיסטית
תחום	סטטיסטיקה למחקר	סטטיסטיקה למחקר
משפחה	Process / pipeline	Process / pipeline
שנת המקור	1988	1925
הוגה השיטה	Jacob Cohen	Ronald Fisher
סוג	Concept	Concept
מקור מכונן	Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences (2nd ed.). Lawrence Erlbaum Associates. ISBN: 0-8058-0283-5	Fisher, R. A. (1925). Statistical Methods for Research Workers. Oliver and Boyd.
כינויים	power analysis, sample size calculation, 1 minus beta, sensitivity	p-value, significance test, statistical significance, alpha level
קשורות	4	5
תקציר	Statistical power is the probability of detecting a true effect if it exists (1 − β). Power analysis determines the sample size required to detect a hypothesized effect size with specified Type I error (α) and Type II error (β) rates. Introduced by Jacob Cohen (1988), power analysis is foundational to research design: underpowered studies produce inflated effect size estimates and are unlikely to replicate. The standard benchmark is 80% power (β = 0.20), though critical studies may require 90% power.	The p-value is the probability of observing data as extreme as or more extreme than what was actually observed, assuming the null hypothesis is true. Introduced by Ronald Fisher in 1925, it is the foundation of frequentist hypothesis testing. Statistical significance is declared when the p-value falls below a pre-specified threshold (alpha level, typically 0.05).