Question 1

What is statistical power?

Accepted Answer

Statistical power is the probability of detecting a true effect when one exists. A power of 80% means you have an 80% chance of finding a significant result if the effect is real.

Question 2

What is a good power level?

Accepted Answer

80% is the common standard, meaning a 20% chance of missing a real effect (Type II error). For critical decisions, 90% or higher may be appropriate.

Question 3

How do sample size and power relate?

Accepted Answer

Larger sample sizes increase power. If your power is too low, you need more participants. If it's already high, you may be able to reduce sample size to save resources.

Question 4

What affects statistical power?

Accepted Answer

Power increases with larger sample sizes, larger effect sizes, higher significance levels (alpha), and lower variance. Adjust these parameters to achieve your target power.

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