April 2016
Intermediate to advanced
384 pages
11h 9m
English
book
Transportation Statistics and Microsimulation
by Clifford Spiegelman, Eun Sug Park, Laurence R. Rilett
Content preview from Transportation Statistics and Microsimulation
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Inferences ◾ 131
very different (e.g., say their ratio is within a factor of 3), then it is generally
advisable to report the pooled t-test results. This is because the pooled t-test is
more widely used and understood than the unequal variance t-test. However,
when the variances are very different, then the separate variance t-test is the
more appropriate of the two tests. Notice that the degrees of freedom for the
two tests are, respectively, 42 and 36 (approximately).
7.5 INFERENCES ABOUT ONE POPULATION VARIANCE
Sometimes the transportation professional is not interested in tests about
the central tendency of the data (e.g., sample