# Web Activities

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#### Calculating power and sample size:

Remember, in 2010, the U.S. census was able to determine that average commute time for U.S. adults is μadults = 22.7, with a standard deviation of σ = 5.5. Given that the researchers believe that students have longer commute times, use the calculator above to determine the statistical power when:

• Mstudents = 23.8, N = 100, α = .05.
• Mstudents = 23.8, N = 150, α = .05.
• Mstudents = 23.8, N = 200, α = .05.
• Mstudents = 23.8, N = 250, α = .05.
• Mstudents = 23.8, N = 300, α = .05.

Remember, in 2010, the U.S. census was able to determine that average commute time for U.S. adults is μadults = 22.7, with a standard deviation of σ = 5.5. Given that the researchers believe that students have longer commute times, use the calculator above to determine the statistical power when:

• Mstudents = 23.8, N = 100, α = .05.
• Mstudents = 24.9, N = 100, α = .05.
• Mstudents = 26.0, N = 100, α = .05.
• Mstudents = 27.1, N = 100, α = .05.
• Mstudents = 28.2, N = 100, α = .05.

Go to this website: https://www.statisticalsolutions.net/pssZtest_calc.php

A recent study measured the differences in SAT scores across income categories. Knowing the mean for the US (μUS = 508, with a standard deviation of σ = 129), and given that the researchers believe that high income test-takers have higher SAT scores than the general public, Given the following situations, calculate the sample sized needed for power = .80 (α = .05) when: (a) δ = .20, (b) δ = .50, and (c) δ = .80.