Question

Children with autism have larger brains than children without the disorder, and the growth appears to occur before age 2, according to a new study released Monday. Previous imaging research found differences in the brains of children with autism and those without. It’s not clear if autism causes the brain changes or if the changes cause autism, a neurodevelopmental disorder characterized by deficits in social interaction and communication. A 2005 study by researchers at the University of North Carolina at Chapel Hill found that 2-year-old children with autism have brains up to 10% larger than children without autism. The study compared the brains of 59 children with autism and 38 without autism. Researchers followed that group and had many of them undergo another magnetic resonance imaging scan when they were 4-or-5-years-old. The study found that children who had enlarged brains at age 2 continued to have enlarged brains at age 4 and 5, but that the rate of growth hadn't increased compared to brains of children without autism. If you look at the actual study referenced in the WSJ article, the study observations were as follows: Sample average brain size for autistic children: 1310.4 cm3 Sample standard deviation: 99.9 cm3 Sample average brain size for normal children: 1238.8 cm3 Sample standard deviation: 111 cm3 Sample size autistic: 59, sample size normal: 38 Use this data to perform a two-sided test for equality of brain size between autistic and non-autistic children. Use alpha = 0.05. Be sure to write down your hypothesis statement. What does the result of the test mean, in words?

Answer 1