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	Analys av statistisk styrka för överlevnadsstudier	Poweranalys för proportionsjämförelser
Ämnesområde	Statistik	Statistik
Familj	Hypothesis test	Hypothesis test
Ursprungsår	1981	1988
Upphovsperson	—	Jacob Cohen
Typ	Sample size determination for survival outcomes	Sample size determination
Ursprungskälla	Schoenfeld, D. A. (1981). The asymptotic properties of nonparametric tests for comparing survival distributions. Biometrika, 68(1), 316–319.	Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences (2nd ed.). Lawrence Erlbaum Associates.
Alias	log-rank power analysis, cox regression power analysis, survival power analysis, Sağkalım Analizi Güç Analizi	proportion power analysis, two-proportion z-test power, z-test for proportions power, Oran Testi Güç Analizi
Närliggande	6	3
Sammanfattning	Power analysis for survival studies determines how many participants — and how many observed events — are required so that a log-rank test or Cox regression has a sufficient probability of detecting a clinically meaningful difference in survival between groups. The foundational formulas were derived by Schoenfeld (1981) and Lachin (1981) and remain the standard approach in clinical trial planning.	Power analysis for proportion tests is a prospective sample-size planning method used to determine how many participants are needed to detect a meaningful difference between two (or one) proportions with a specified probability. Formalised by Jacob Cohen in his 1988 landmark text, it applies the arcsine transformation to convert proportions into the effect-size index h, enabling direct calculation of the required sample size.