MeanTestingHandout

# MeanTestingHandout - =.159 Is the difference in crop yield...

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POLS4150: H YPOTHESIS T ESTING DIFFERENCE OF MEANS For each, state the null hypothesis and conduct the test for the difference of means. 1. The Department of Agriculture wants to test the effect that a new fertilizer has on wheat production. To accomplish this, a sample of 25 plots of land having equal areas are chosen. 12 of these were treated with the fertilizer and the other 13 were untreated. The mean yield of wheat on the untreated plots was 4.8 bushels with a standard deviation of 0.40 bushels, while the mean yield on the treated plots was 5.1 bushels with a standard deviation of 0.36 bushels. The standard error of the differences between the means is
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Unformatted text preview: = .159. Is the difference in crop yield between the two plots statistically significant at the alpha level of .05? 2. A report on salary levels for full professors in the social sciences at public research universities provides the following data for separate samples of men and women. The 400 men sampled earned an average salary of \$80,000 and the 50 women sampled earned an average salary of \$70,000. The standard error of the difference between these two means is \$3,000. Is the difference statistically significant at the alpha level of .05? At the .01 level? What is the exact p-value? Interpret the p-value....
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## This note was uploaded on 10/25/2010 for the course POLI 4150 taught by Professor Wilk during the Fall '10 term at UGA.

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