lecture11-2

# 2 set up the study as described above and derive the

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Unformatted text preview: l hypothesis) and what we OBSERVED. How big is this difference? We will measure it using a new statistic called the chi- squared statistic. To calculate the chi- square statistic: 1. Find (O – E) for each of the four cells. That is, (observed value – expected value). 2. Square the values from step 1. You should notice that they are all the same. 3. Divide each of the values from step 2 by the expected values in each cell. 4. Add the values in step 3. The result is referred to as chi- squared. 2 (observed − expected) 2 Χ=∑ expected all cells In our example, we have: 2 2 2 2 (50 − 42) + (100 − 108) + (34 − 42) + (116 − 108) = 4.2 chi- squared= 42 108 42 108 € We use this number to test our hypothesis as follows: 1. State the null hypothesis: There is no relationship between chewing Nicorette and getting a sore throat. Specifically, you are no more or less likely to get a sore throat after chewing Nicorette than after chewing a placebo gum. 2. Set up the study as described above and derive the EXPECTED and OBSERVED values for the four cells....
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## This document was uploaded on 12/11/2013.

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