Part A: Analysis of traffic data                     

 In this section you will use the data you collected in Assignment 1.

 1. Comparing two means:

a) Confidence interval for difference between means

 (i) Use Minitab to construct a 95% Confidence Interval for the difference between the means of your numeric variable for the different levels of your 2-level categorical variable.                                                                                                               

(ii) Interpret your confidence interval in context (remember units).

(iii) Use your confidence interval to draw a conclusion about the difference (if any) between the two levels of your categorical variable.

 b) Two-tailed hypothesis test for the difference between two means

(i) State the null and alternative hypotheses (in words and symbols) for testing if there is a significant difference between the means of your numeric variable for the different levels of your 2-level categorical variable.

(ii) Use Minitab to carry out the test. State the test statistic and corresponding p-value for these hypotheses.

(iii) Explain whether you have evidence for or against the null hypothesis.

(iv) State your conclusion in a form that a non-statistician would understand.