The difference from the hypothesized mean is 2, the population standard deviation is 5, and a two-tailed significance test is performed at the 0.05 level. About what sample size would be needed for a power of .8?
52 subjects are needed for power of .8.
52
8
Set the simulation to use these parameters and examine the graph for the 0.05 level and estimate the sample size required for power to be 0.8.
The difference from the hypothesized mean is 2, the population standard deviation is 5, and a one-tailed significance test is performed at the 0.05 level. About what sample size would be needed for a power of .8?
41 subjects are needed for power of .8. Note this is fewer than the 52 subjects needed when a two-tailed test was conducted.
41
8
Set the simulation to use these parameters and examine the graph for the 0.05 level and estimate the sample size required for power to be 0.8.
The difference from the hypothesized mean is 4, the population standard deviation is 5, the sample size is 15. Estimate the power for a two-tailed test at the 0.05 level.
The power would be .82
.82
.10
Set the simulation to use these parameters and examine the graph for the 0.05 level and estimate the power for a sample size of 15.
The difference from the hypothesized mean is 4, the population standard deviation is 5, the sample size is 15. Estimate the power for a two-tailed test at the 0.01 level.
The power would be .56. Note that this is lower than the power of .82 for the .05 level.
.56
.10
Set the simulation to use these parameters and examine the graph for the 0.01 level and estimate the power for a sample size of 15.