Statistical Power and Extensive Variance of Outcome

Extensive variance in the outcome decreases statistical power and increases the needed sample size.

Statistical Power and Limited Variance of Outcome

Limited variance in the outcome will increase statistical power and decrease the needed sample size.

Statistical Power and Variance of Outcome

Variance of an outcome has implications on statistical power and the needed sample size.

Statistical Power and Large Effect Sizes

Large effect sizes increase statistical power and decrease the needed sample size.

Statistical Power and Small Effect Sizes

Small effect sizes decrease statistical power and increase the needed sample size.

Statistical Power and Effect Size

Statistical power is greatly impacted by the magnitude and variance of the effect size.

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Retrospective cohort designs can yield measures of risk and longitudinal effects.