In a study of the cognitive skills required for successful arguments, 62 psychology graduate students were equally divided into two groups.

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In a study of the cognitive skills required for successful arguments, 62 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 nonfavored position. If you compare the mean ratings for the two groups with a small-sample t-test, assuming equal variances, determine the validity of this assumption at a= 0.05.

 Group 1 (Support favored position) Group 2(Weaken opposing position) Sample size 31 31 Mean 28.8 25.2 Standard deviation 12.8 12.2

We test the assumption that the mean for Group 1 is greater than the mean for group 2,

Two-Sample T-Test and CI

Sample   N  Mean  StDev  SE Mean
1       31  28.8   12.8      2.3
2       31  25.2   12.2      2.2

Difference = μ (1) - μ (2)
Estimate for difference:  3.60
95% lower bound for difference:  -1.71
T-Test of difference = 0 (vs >): T-Value = 1.13  P-Value = 0.131  DF = 59

Fail to reject the null hypothesis, there is no evidence that the group effects are significant.