EC315 #40 Help

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

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
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
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

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....
View Full Document

This note was uploaded on 11/11/2011 for the course EC 315 taught by Professor Barcus during the Spring '10 term at Park.

Ask a homework question - tutors are online