Simple pre-post designs where the outcome assessed is continuous. Using pwrss package

pwrss.t.2means(
                mu1 = 37.86, sd1 = 16.12, 
                mu2 = 24.80, sd2 = 14.46, 
                paired = TRUE, paired.r = 0.50,
                power = .90, alpha = 0.05,
                alternative = "not equal")Code language: PHP (php)

Output

 Difference between Two means 
 (Paired Samples t Test) 
 H0: mu1 = mu2 
 HA: mu1 != mu2 
 ------------------------------ 
  Statistical power = 0.9 
  n = 17 
 ------------------------------ 
 Alternative = “not equal” 
 Degrees of freedom = 16 
 Non-centrality parameter = 3.506 
 Type I error rate = 0.05 
 Type II error rate = 0.1

References

• https://cran.r-project.org/web/packages/pwrss/vignettes/examples.html#paired-samples-t-test