12. Comparing ANOVA and the t test for an independent-measures hypothesis test Suzanne Zeedyk, a developmental psychologist at Dundee University's School of Psychology, conducted a pilot study in which parents started a half- hour walk with their infants in a parent-facing or an away-facing stroller and then switched to the other type of stroller midway. Her results suggest that parents talked less to the babies, the babies had higher heart rates, and they were less likely to fall asleep in away-facing strollers than in parent- facing strollers. You are interested in testing the hypothesis that babies who travel in parent-facing strollers have different receptive vocabularies than babies who travel in away-facing strollers. You randomly assign 12 newborns to parent-facing strollers and 12 newborns to away-facing strollers. You then test the babies' receptive vocabularies at age 18 months using the Peabody Picture Vocabulary Test-Revised (PPVT-R), which is designed primarily to assess children's receptive vocabulary. The sample means and sums of squares of the scores for each of the groups are presented in the following table. Group Away-facing Parent-facing Sample Mean Sum of Squares 98.1 2,064.59 106.2 1,404.59 You decide to use an ANOVA at o 0.01 to test the null hypothesis that there is no difference between the groups. The ANOVA table follows. Calculate the F-ratio and enter it into the table.