Imagine that one of the following 95 percent con?dence intervals estimates the effect of vitamin C on IQ scores:
95% confidence interval: 1,2,3,4,5
Lower limit: 100,95,102,90,91
Upper limit: 102,99,106,111,98
(a) Which one most strongly supports the conclusion that vitamin C increases IQ scores?
(b) Which one implies the largest sample size?
(c) Which one most strongly supports the conclusion that vitamin C decreased IQ scores?
(d) Which one would most likely stimulate the investigator to conduct an additional experiment using larger sample sizes?