EC315 #40 Help

# EC315 #40 Help - number of traffic accidents? You must use...

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Can you help me with this problem? I am having trouble getting started. A number of minor automobile accidents occur at various high-risk intersections in Teton County despite traffic lights. The Traffic Department claims that a modification in the type of light will reduce these accidents. The county commissioners have agreed to a proposed experiment. Eight intersections were chosen at random, and the lights at those intersections were modified. The numbers of minor accidents during a six-month period before and after the modifications were: Number of Accidents A B C D E F G H Before modification 5 7 6 4 8 9 8 10 After modification 3 7 7 0 4 6 8 2 At the .01 significance level is it reasonable to conclude that the modification reduced the
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Unformatted text preview: number of traffic accidents? You must use excel test functions. Solution. Null hypothesis H0: the modification didnt reduce the number of traffic accidents Alternative hypothesis H1: the modification reduced the number of traffic accidents Use Excel, we get t-Test: Paired Two Sample for Means Variable 1 Variable 2 Mean 7.125 4.625 Variance 4.125 7.982143 Observations 8 8 Pearson Correlation 0.308088 Hypothesized Mean Difference df 7 t Stat 2.415229 P(T<=t) one-tail 0.023208 t Critical one-tail 1.894579 P(T<=t) two-tail 0.046416 t Critical two-tail 2.364624 From the above table, we know that the p-value is 0.023208 which is greater than alpha=0.01 So, we fail to reject the null hypothesis H0. We conclude that the modification didnt reduce the number of traffic accidents. Note: This is a paired test for two population means....
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## This note was uploaded on 11/11/2011 for the course EC 315 taught by Professor Barcus during the Spring '10 term at Park.

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