Transportation Statistics and Microsimulation

144    ◾    Transportation Statistics and Microsimulation

To illustrate these methods, we reanalyze the data from San Antonio

used in Figure 2.3. e dependent variable is average speed along the cor-

ridor, and the factor that we use is the number of trac signals on the

corridor. We present the JMP output in Figure 8.3.

e rst observation that can be made from the output of Figure 8.3

is that even small dierences in the populations can be detected as sta-

tistically signicant due to the relatively large sample sizes. From Fisher’s

LSD procedure (given under “Comparisons for each pair using Student’s

t” in Figure 8.3) we can see that only t