27.7 T-Test

• Determine the effect size you can find with 10 samples

p <- pwr.t.test(n=10, d=NULL,
                sig.level=0.05, power=0.8, type="two.sample")
p

## 
##      Two-sample t test power calculation 
## 
##               n = 10
##               d = 1.3
##       sig.level = 0.05
##           power = 0.8
##     alternative = two.sided
## 
## NOTE: n is number in *each* group

• Hence, we expect to be able to detect and effect size that is 1.32 × σ where σ is the standard deviation of the sample.
• However, we do not know what the σ will be