From the course: Six Sigma: Green Belt

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Test for independence

Test for independence

From the course: Six Sigma: Green Belt

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Test for independence

- Let's talk about testing for independence. And by way of example, we'll use everybody's favorite topic, hospitals. Let's say your grandmother needs to undergo surgery and there are four hospitals in the local area. Should it matter which hospital she chooses? Is the outcome independent of or dependent on the choice of hospital? To test this, the appropriate hypothesis test is the chi-square test for association, also called the test for independence. The null hypothesis is outcome Y is independent of factor X. And the alternate is outcome Y is not independent, in other words, it is dependent on factor X. In our example, there are four hospitals that perform the same surgery. The possible outcomes are: full recovery, partial recovery, and death. The table shows the number of surgeries performed at each hospital and their outcomes for the past 12 months. The practical theory or question is, does the choice of hospital…

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