136 Accuracy of mental maps. To help students organize global information about people, places, and environments, geographers encourage them to develop “mental maps” of the world. A series of lessons was designed to aid students in the development of mental maps ( Journal of Geography, May/June 1997). In one experiment, a class of 24 seventh-grade geography students was given mental map lessons, while a second class of 20 students received traditional instruction. All of the students were asked to sketch a map of the world, and each portion of the map was evaluated for accuracy on a five-point scale

(1 = low accuracy, 5 = high accuracy).

a. The mean accuracy scores of the two groups of seventhgraders were compared with the use of a test of hypothesis.

State H0 and Ha for a test to determine whether the mental map lessons improve a student’s ability to sketch a world map.

b. The observed significance level of the test for comparing the mean accuracy scores for continents drawn is

.0507. Interpret this result.

c. The observed significance level of the test for comparing the mean accuracy scores for labeling oceans is

.7371. Interpret the result.

d. The observed significance level of the test for comparing the mean accuracy scores for the entire map is .0024.
Interpret the result.

e. What assumptions (if any) are required for the tests to be statistically valid? Are they likely to be met? Explain.