Question 14.47

14.47 Time levels of scale, continued.

Refer to the previous exercise.

timescl

  1. Run the ANOVA and report the results.
  2. Use a multiple-comparisons method to compare the three groups. State your conclusions.
  3. The researchers hypothesized that the more fine-grained the time unit presented to a participant, the smaller the reported interval would be. To test this, they performed a simple linear regression using the group labels 1, 2, and 3 as the predictor variable. They found the slope significantly different from 0 and thus concluded the data supported their hypothesis. Do you think this is an appropriate way to test their hypothesis? Explain your answer.

14.47

(a) not all of the are equal, . There are significant interval differences among the three groups. (b) The Bonferroni procedure shows that group 2 is not significantly different from either group 1 or group 3; however, group 3 is significantly different (larger) than group 1. (c) This is not appropriate. The regression assumes that group 2 (coded as 2) would have twice the effect of group 1 (coded as 1), and group 3 (coded as 3) would have 3 times the effect of group 1, etc. This is likely not true.