# power.ftest: Power Calculations for an F-test In Superpower: Simulation-Based Power Analysis for Factorial Designs

## Description

Compute power of test or determine parameters to obtain target power. Inspired by the pwr.f2.test function in the pwr package, but allows for varying noncentrality parameter estimates for a more liberal (default in pwr.f2.test) or conservative (default in this function) estimates (see Aberson, Chapter 5, pg 72).

## Usage

 ```1 2 3 4 5 6 7 8``` ```power.ftest( num_df = NULL, den_df = NULL, cohen_f = NULL, alpha_level = Superpower_options("alpha_level"), beta_level = NULL, liberal_lambda = Superpower_options("liberal_lambda") ) ```

## Arguments

 `num_df` degrees of freedom for numerator `den_df` degrees of freedom for denominator `cohen_f` Cohen's f effect size. Note: this is the sqrt(f2) if you are used to using pwr.f2.test `alpha_level` Alpha level used to determine statistical significance. `beta_level` Type II error probability (power/100-1) `liberal_lambda` Logical indicator of whether to use the liberal (cohen_f^2\*(num_df+den_df)) or conservative (cohen_f^2\*den_df) calculation of the noncentrality (lambda) parameter estimate. Default is FALSE.

## Value

num_df = degrees of freedom for numerator, den_df = degrees of freedom for denominator, cohen_f = Cohen's f effect size, alpha_level = Type 1 error probability, beta_level = Type 2 error probability, power = Power of test (1-beta_level\*100 lambda = Noncentrality parameter estimate (default = cohen_f^2\*den_df, liberal = cohen_f^2\*(num_df+den_df))

## References

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale,NJ: Lawrence Erlbaum. Aberson, C. (2019). Applied Power Analysis for the Behavioral Sciences (2nd ed.). New York,NY: Routledge.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11``` ```design_result <- ANOVA_design(design = "2b", n = 65, mu = c(0,.5), sd = 1, plot = FALSE) x1 = ANOVA_exact2(design_result, verbose = FALSE) ex = power.ftest(num_df = x1\$anova_table\$num_df, den_df = x1\$anova_table\$den_df, cohen_f = x1\$main_result\$cohen_f, alpha_level = 0.05, liberal_lambda = FALSE) ```

Superpower documentation built on May 25, 2021, 9:07 a.m.