To investigate if autism is marked by different brain growth

To investigate if autism is marked by different brain growth patterns in early life, studies have tried to link brain size in infants and toddlers to autism. Suppose the whole-brain volume in non-autistic toddlers is known to be 1200 millilitres, on average. One study based on a sample size of 35 estimated the mean whole-brain volume in autistic toddlers with a 95% confidence interval of [1220 ml, 1400 ml]. Do the results from this study suggest that autistic toddlers have the same whole-brain volume, on average? If you used the same data from this study and calculated a 90% confidence interval, would it be wider or narrower than the 95% interval? If the data from this study had the same mean and standard deviation, but was from a sample of size 70 instead of 35, would the 95% confidence have been wider or narrower?

Solution

a)
NO, since the sample does n\'t contian the value of population mean

b)
It would be narrower

c)
When value of n is large, stanadrd error will be decreased, & that result in narrowing interval