
Vehicle Evaluation Methods 263
Step 6: Computation of Z Values and Scale Values for the Products
In this step, the values of the proportions (p
ij
) in each cell are converted into Z values by using the
table of standardized normal distribution found in any standard statistics textbook. For example, the
value of p
21
= .023 is obtained by integrating the area under the standardized normal distribution
TABLE 15.4
Responses of an Individual
Subject for the Ten Possible
Product Pairs
S W N P K
S
X No No No No
W
X No No Yes
N
X No Yes
P
X Yes
K
X
Note: A “yes” response indicates that the
product shown in the column is
better than the product ...