Transportation Statistics and Microsimulation

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9Chapter

Inferences Concerning

Categorical Data

9.1 INTRODUCTION

In Chapter 3, we introduced the concept of proportion(s) as a summary of

categorical data. As you may recall, this type of data occurs relatively oen

in transportation. For example, the U.S. Federal Highway Administration

(FHWA) groups vehicles into thirteen distinct types, and a good portion of

survey data is categorical in nature. Consequently, transportation engineers

use and test proportions quite oen. We may wish to know if an education

program decreases the percentage of teen drivers who are texting while

driving. In another situation, we may want to know if there ...