w 18 -- 21 A researcher wants to determine if an antioxidant supplement made from blueberries affects the cognitive func

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W 18 21 A Researcher Wants To Determine If An Antioxidant Supplement Made From Blueberries Affects The Cognitive Func 1 (22.63 KiB) Viewed 15 times

w 18 -- 21 A researcher wants to determine if an antioxidant supplement made from blueberries affects the cognitive functioning of elderly adults. A sample of n = 16 adults between the ages of 65 and 75 is obtained. The researcher uses a standardized test to measure cognitive performance for each individual. The participants then begin a two-month program in which they receive daily doses of the blueberry supplement. At the end of the two-month period, the researcher again measures cognitive performance for each participant. If you were to perform a two-tailed test on the data from the participants' test scores, what degrees of freedom would you use to look up the critical value for evaluating the null hypothesis?