Refer to the Thinking and Reasoning (Oct. 2006) study of the cognitive skills required for successful arguments, presented in Exercise 9.25 (p. 451). Recall that 52 psychology graduate students were equally divided into two groups. Group 1 was presented with arguments that always attempted to strengthen the favored position. Group 2 was presented with arguments that always attempted to weaken the non favored position. Summary statistics for the student ratings of the arguments are reproduced in the accompanying table. In Exercise 9.25, you compared the mean ratings for the two groups with a small-sample t-test, assuming equal variances. Determine the validity of this assumption at α = .05.

Group 1 (support favored (weaken opposing position) Group 2 position) Sample size 26 28.6 12.5 26 24.9 12.2 Mean Standard deviation