A study was conducted to compare cognitive development of low-birthweight and normal-birthweight babies at one year of age. Cognitive development was scored from 0-30, with 0 being very low cognitive development and 30 being excellent cognitive development. The sample mean of low-birthweight babies was 16.8 and that of normal-birthweight babies was 22, with a pooled standard deviation of 8. Each group had an equal sample size of 8.

Using R's function for power, double-check your power calculation using the effect size you calculated above and enter in the values from the R output below. R calculates the power more exactly, so it will have a slightly different value than what you entered above. Round to two decimal places when needed.