Two different red-light-running signal systems were installed at various interse

Question

Two different red-light-running signal systems were installed at various intersection locations with the goal of reducing angle-type crashes. Red-Light-Running System A resulted in 60% angle crashes over a sample of 720 total crashes. Red-Light-Running System B resulted in 52% angle crashes over a sample of 680 total crashes. Was there a difference between the proportions of angle crashes between the two red-light-running systems installed? Use an alpha of 0.10. (8 points)

What test should be utilized for this analysis? (1 point)

What is critical statistic for this test? (1 point)

What is calculated statistic for this test? (1 point)

What is the proportional rate for A? (1 point)

What is the proportional rate for B? (1 point)

What is the conclusion of the analysis? (1 point)

Explanation / Answer

Solution

(a) Two proportion z test will be used to test the  difference between the proportions of angle crashes between the two red-light-running systems installed.

(b) z critical value : +-1.6449

(c) Z test statistic : (0.6-0.52)/((0.6)(0.4)/720 + (0.52)(0.48)/680))0.5 = 3.0229

(d) Proportion rate for A = 0.60

(e) Proportional rate for B = 052

(f) Conclusion : we can conclide that there was a difference between the proportions of angle crashes between the two red-light-running systems installed as z critical value < z test statistic

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