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Minitab 15 Tutorial:
Using Power and Sample Size Tools with Power Curves

For any job, you need a tool that offers the right amount of power. You don’t use a telescope to examine a stamp collection or a handheld magnifying glass to search for new galaxies because neither provide you with meaningful observations. To complicate matters, the cost of achieving the necessary power might be more than you can afford.

Anyone who uses statistical tests faces the same issues. You must consider the precision that you need to meet your goals (should your test detect subtle effects or massive shifts?) and balance it against the cost of sampling your population (are you testing toothpicks or jet engines?). You also want the confidence in your results that’s appropriate for your situation (tests for seat belts demand a greater degree of certainty than tests for shampoo require). We can measure this certainty using statistical power—the probability that your test will detect an effect that truly exists.

Minitab’s Power and Sample Size tools, with Power Curves, help you to balance these issues that may compete for your limited resources. Here are three examples of how a quick Power and Sample Size test can help you to save time and money, while still providing results that you can trust.