TECNOLOGIA DE TRANSPORTE INTERNO

Table 5.5 contains the summary of the analyses of each question in Scenario 1 (Sites A and B). The first column is the within-subjects t-test that compared the response about the phone in Site A to the response about the phone in Site B. The second column is the corresponding correlation between responses about Site A and responses about Site B. The third column is the within-subject t-test that compared the response about the phone cover in Site A to the response about the phone cover in Site B. The fourth column is the corresponding correlation between responses about Site A and responses about Site B.

Table 5.5 Test of the Differences between Means for Sites A and B.

Expensive

(Mobile phone) (Mobile phone cover) Inexpensive

Questions t-test Correlation t-test Correlation

1.The website was easy to

navigate _{p <.146} 1.56, _{p <.831} 0.069, _{p <.009} 3.17, _{p <.353} -0.294, 2. Navigating to the item was easy 0.80,

p <.438 -0.057, p <.860 2.25, p <.046 -0.143, p <.658

3. The navigation was helpful to

reach the item I wanted to buy _{p <.006} 3.36, _{p <.956} 0.018, _{p <.097} 1.82, _{p <.834} 0.068, 4. The images were easy to view 0.43,

p <.674 -0.182, p <.572 -0.27, p <.791 0.031, p <.925

5. Product information was

complete _{p <.222} 1.30, _{p <.193} 0.404, _{p <.039} 2.35, _{p <.100} 0.497, 6. Checking out was organized 3.14,

p <.009 p <.866 -0.055, p <.005 3.53, p <.354 -0.294,

7. The layout of the items made it

easier to choose _{p <.007} 3.29, _{p <.999} 0.000, _{p <.095} 1.83, _{p < .604} -0.167, 8. The sizes of the images made it

easier to buy an item _{p <.266} -1.17, _{p <.406} -0.265, _{p <.191} -1.39, _{p <.738} -0.108, 9. The color scheme is appropriate 3.54,

p <.005 -0.732, p <.007 1.62, p <.133 -0.153, p <.636

10. The website is professional 6.61, p <.001 -0.214, p <.505 2.19, p <.051 -0.311, p <.325

To interpret, note that for the expensive item (Phone), the questions 1, 2, 4, 5 and 8 were not significantly different between sites. That is, for these questions, responses about Sites A and B were (statistically) the same.

However, questions 3, 6, 7, 9 and 10 did show significant differences and Site A was generally higher. In particular, the differences were large in Questions 9 and 10.

For the Inexpensive item (Phone cover), the pattern was a little different.

Questions 3, 4, 7, 8, 9, and 10 were not significantly different between sites. On the other hand, Questions 1, 2, 5, and 6 were significantly different. Again, Site A received the higher ratings. Note that only Question 6 was different for both the Expensive and Inexpensive items. As noted in Table 5.2, Site B should have been higher for Questions 2, 3, 4, 5, and 8.

Finally, it could be noted that Table 5.4 includes the correlations between

responses across participants (Table 5.3, Columns 2 and 4). If the correlation is positive, it is implied that there is a tendency for those participants who rated Site A highly to also rate Site B highly (and vice versa). A positive correlation would likely reflect individual differences in website design (e.g., it could be a preference for the common elements that donot change between Sites A and B, or general experience, frustration tolerance, or even simply, visual acuity). Conversely, if the correlation is negative, then there is a tendency for those participants who rated Site A high to also rate Site B low (and vice versa). A negative correlation implies a contrast effect (e.g., after rating Site A highly, Site B seems really poor). As it happened, the correlations were a mix of positive and negative. Furthermore, only two correlations were significant and both of those were negative.

It should be noted that the correlation is actually an important component of the statistical test itself – if the correlations are low (or negative), the within-subjects t-test is less likely to be significant. Technically, the power of the within-subjects t-test to detect differences between the means depends on the magnitude of the correlation. Some people go as far as stating that a positive correlation is an assumption of the t-test, but that is overstating the case. Regardless of the sign or magnitude of the correlation, the final p- value (significance) is an accurate reflection of the probably of getting mean difference that is this large or large from this particular population. The key point is that when the

correlation is negative, large mean differences are required for “significance”, and in some sense, the mean difference is simply less interpretable. Table 5.6 presents the same analysis for Scenario 2: Watch and Gift Box.

Table 5.6 Test of the Differences between Means for Sites C and D.

Expensive

(Watch) Inexpensive(Gift box)

Question t-test correlation t-test Correlation

1.The website was easy to navigate 0.10, p <.920 -0.502, p <.096 -0.13, p <.898 -0.082, p <.801

2. Navigating to the item was easy -0.71,

p <.491 p <.710 -0.120, p <.499 -0.70, p <.560 -0.187,

3. The navigation was helpful to reach

the item I wanted to buy _{p <.409} 0.86, _{p <.931} 0.028, _{p <.480} 0.73, _{p <.466} -0.233, 4. The images were easy to view 0.97,

p <.353 -0.539, p <.071 -3.71, p <.003 0.462, p <.130

5. Product information was complete 1.27, p <.232 0.510, p <.090 0.81, p <.437 -0.443, p <.149

6. Checking out was organized 0.00, p <.999 -0.288, p <.364 -4.05, p <.002 0.160, p <.619

7. The layout of the items made it

easier to choose _{p <.489} 0.72, _{p <.007} -0.726, _{p <.249} -1.22, _{p <.443} -0.245, 8. The sizes of the images made it

easier to buy an item _{p <.065} 2.05, _{p <.635} -0.153, _{p <.003} -3.87, _{p <.415} 0.260, 9. The color scheme is appropriate 1.04,

p <.323 p <.002 -0.800, p <.137 -1.60, p <.717 -0.117,

10. The website is professional -0.38,

p <.710 p <.163 -0.430, p <.018 -2.78, p <.626 0.157, To interpret, note that for the Expensive item (Watch), there are no significant differences for any questions. For the Inexpensive item, Questions 4, 6, 8, and 10 showed significant differences. It was Site D that always received the higher ratings.

Finally, it could be noted that the correlations (in Table 5.5) between responses across participants (Table 5.3, Columns 2 and 4) were a mixed of positive and negative, but only two were significant. These likely reflect a contrast effect.

In summary, one can conclude that there are differences between Sites A and B, and that there are differences between Sites C and D. However, the differences between C and D are less pronounced and only occur for the Inexpensive item. Generally, the

differences do depend, to some degree, on item Price. Nonetheless, the patterns of responses for Expensive and Inexpensive items were correlated within each site.

5.1.6 Differences between Expensive and Inexpensive Items in