Standard Deviations	Sample Sizes	Assume Equal Standard Deviations (Pooled)	Do Not Assume Equal Standard Deviations (Not Pooled)
Study					T test statistic	Degrees of Freedom	P-value	T test statistic	Degrees of Freedom	P-value
1	12	10	20	20	1.431	38	0.1605	1.431	36.80	0.1607
2	12	10	50	50	2.263	98	0.0258	2.263	94.91	0.0259
3	6	5	20	20	2.863	38	0.0068	2.863	36.80	0.0069
4	6	6	32	8	2.108	38	0.0417	2.108	10.79	0.0593
5	8	6	20	20	2.236	38	0.0313	2.236	35.24	0.0318
6	8	6	10	30	2.097	38	0.0427	1.814	12.55	0.0937
7	8	6	30	10	1.808	38	0.0785	2.088	20.58	0.0494
8	12	2	20	20	1.838	38	0.0739	1.838	20.05	0.0809
9	12	2	10	30	2.246	38	0.0306	1.312	9.17	0.2216
10	12	2	30	10	1.301	38	0.2012	2.193	33.29	0.0354

What do we learn from this? Answer the following questions.

1. Compare "Pooled" and "Not Pooled" from Study 4: What is the benefit in assuming that standard deviations are equal (when they are exactly equal)? Which of our three metrics does this assumption not affect and which does this assumption affect and in what way?