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The Role of Statistics in
Engineering
Statistics is a science that helps us make decisions and draw
Chapter Outline conclusions in the presence of variability. For example, civil
engineers working in the transportation i eld are concerned
1-1 The Engineering Method and Statistical about the capacity of regional highway systems. A typical
Thinking problem related to transportation would involve data regarding
this speciic system’s number of nonwork, home-based trips,
1-2 Collecting Engineering Data the number of persons per household, and the number of vehi-
1-2.1 Basic Principles cles per household. The objective would be to produce a trip-
1-2.2 Retrospective Study generation model relating trips to the number of persons per
1-2.3 Observational Study household and the number of vehicles per household. A statis-
1-2.4 Designed Experiments tical technique called regression analysis can be used to con-
1-2.5 Observing Processes Over Time struct this model. The trip-generation model is an important
1-3 Mechanistic and Empirical Models tool for transportation systems planning. Regression methods
are among the most widely used statistical techniques in engi-
1-4 Probability and Probability Models neering. They are presented in Chapters 11 and 12.
The hospital emergency department (ED) is an important
part of the healthcare delivery system. The process by which
patients arrive at the ED is highly variable and can depend on
the hour of the day and the day of the week, as well as on
longer-term cyclical variations. The service process is also
highly variable, depending on the types of services that the
patients require, the number of patients in the ED, and how the
ED is staffed and organized. An ED’s capacity is also limited;
consequently, some patients experience long waiting times.
How long do patients wait, on average? This is an important
question for healthcare providers. If waiting times become
excessive, some patients will leave without receiving treatment
LWOT. Patients who LWOT are a serious problem, because
they do not have their medical concerns addressed and are at
risk for further problems and complications. Therefore, another
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