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Updated: Jun 28, 2026

Design and Optimization Strategies of a High-Performance Vented Box
Published on: June 9, 2023
[Design and power analysis: n and confidence intervals of means]
José Fernando García1, Juan Pascual, María Dolores Frías
1Facultad de Psicología, Universidad de Valencia, Valencia, Spain. fernando.garcia@uv.es
Abstract:
In this study, we analyzed the validity of the conventional 80% power. The minimal sample size and power needed to guarantee non-overlapping (1-alpha)% confidence intervals for population means were calculated. Several simulations indicate that the minimal power for two means (m = 2) to have non-overlapping CIs is .80, for (1-alpha) set to 95%. The minimal power becomes .86 for 99% CIs and .75 for 90% CIs. When multiple means are considered, the required minimal power increases considerably. This increase is even higher when the population means do not increase monotonically. Therefore, the often adopted criterion of a minimal power equal to .80 is not always adequate. Hence, to guarantee that the limits of the CIs do not overlap, most situations require a direct calculation of the minimum number of observations that should enter in a study.
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