11.48 Terrain Visualization A study was con- ducted to determine the effect of two factors on terrain visualization training for soldiers. During the training programs, participants viewed contour maps of various terrains and then were permitted to view a computer reconstruction of the terrain as it would appear from a specified angle. The two factors investigated in the experiment were the participants' spatial abilities (abili- ties to visualize in three dimensions) and the viewing procedures (active or passive). Active participation permitted participants to view the computer-generated reconstructions of the terrain from any and all angles. Passive participation gave the participants a set of preselected reconstructions of the terrain. Participants were tested according to spatial ability, and from the test scores 20 were categorized as possessing high spatial ability, 20 medium, and 20 low. Then 10 participants within each of these groups were assigned to each of the two training modes, active or passive. The accompanying tables are the ANOVA table computed by the researchers and the table of the treatment means.

a. Explain how the authors arrived at the degrees of freedom shown in the ANOVA table.

b. Are the F-values correct?

c. Interpret the test results. What are their practical implications?

d. Use Table 6 in Appendix I to approximate the p-values for the F statistics shown in the ANOVA table.

Source Error df MS df F p Main effects: Training condition 1 103.7009 54 3.66 0.0610 Ability 2 760.5889 54 26.87 0.0005 Interaction: Training condition X Ability 2 Within cells 124.9905 54 28.3015 54 4.42 0.0167 Training Condition Spatial Ability Active Passive High 17.895 9.508 Medium 5.031 5.648 Low 1.728 1.610 Note: Maximum score = 36.