Do girls think they don’t need to take as many science classes as boys? The article “Intentions of Young Students to Enroll in Science Courses in the Future: An Examination of Gender Differences” (Science Education [1999]: 55– 76) gives information from a survey of children in grades 4, 5, and 6. The 224 girls participating in the survey each indicated the number of science courses they intended to take in the future, and they also indicated the number of science courses they thought boys their age should take in the future. For each girl, the authors calculated the difference between the number of science classes she intends to take and the number she thinks boys should take.
a. Explain why these data are paired.
b. The mean of the differences was -.83 (indicating girls intended, on average, to take fewer classes than they thought boys should take), and the standard deviation was 1.51. Construct and interpret a 95% confidence interval for the mean difference.