Suppose that the 101 randomly selected eighth-grade students (mentioned in question 6) took a “practice” test similar to the official standardized test a month before the official test was administered. The researchers reported that the (two-tailed) statistical test of the difference between the practice and official test scores resulted in t100 = -2.32, p < .05. (a) Given that the difference score was computed as D = (practice score – official score), do the reported results indicate that students scored significantly higher or lower on the official test relative to the practice test? Explain. (b) If we constructed the corresponding 95% confidence interval for the mean difference (between the practice and official test scores) in the population, would it include zero? Explain.
Suppose that the 101 randomly selected eighth-grade students (mentioned in question 6) took a “practice” test similar to the official standardized test a month before the official test was administered. The researchers reported that the (two-tailed) statistical test of the difference between the practice and official test scores resulted in t100 = -2.32, p < .05.
(a) Given that the difference score was computed as D = (practice score – official score), do the reported results indicate that students scored significantly higher or lower on the official test relative to the practice test? Explain.
(b) If we constructed the corresponding 95% confidence interval for the
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