Question

A researcher begins with a known population—in this case, scores on a standardized test that are normally distributed with µ = 75 and σ = 15. The researcher suspects that special training in reading skills will produce a change in the scores for the individuals in the population. Because it is not feasible to administer the treatment (the special training) to everyone in the population, a sample of n = 25 individuals is selected, and the treatment is given to this sample. Following treatment, the average score for this sample is M = 90. Is there evidence that the training has an effect on test scores? Test at alpha α = 0.05. What is the critical value for this hypothesis test?

          A researcher begins with a known population—in this case, scores on a standardized test that are normally distributed with µ = 75 and σ = 15. The researcher suspects that special training in reading skills will produce a change in the scores for the individuals in the population. Because it is not feasible to administer the treatment (the special training) to everyone in the population, a sample of n = 25 individuals is selected, and the treatment is given to this sample. Following treatment, the average score for this sample is M = 90. Is there evidence that the training has an effect on test scores? Test at alpha α = 0.05. What is the critical value for this hypothesis test?

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