Question

Autism may be marked by different patterns of brain growth during early life. Researchers measured brain volume (in milliliters, using an MRI) in 32 boys who were later diagnosed with autism. Brain volume is also available for 10 boys who did not develop autism; these 10 boys serve as the control group. The sample statistics are presented for both groups in the table below. Assume that the population variances are equal. Use a sigificance level of 0.05 to test for a difference between the autism and control groups.

Q: The 90% confidence interval for the true difference between brain volumes is (give answers to two places after decimal):

lower bound: upper bound:

Groups	Sample size	Sample mean	Sample SD
Autism (group 1)	n1 = 32	y1 = 1300.53	s1 = 86.6
Control (group 2)	n2 = 10	y2 = 1190.05	s2 = 68.36

Answer 1

The statistical software output for this problem is :

The 90% confidence interval for the true difference between brain volumes is (59.94 , 161.2)