# Question: The teacher from Problem 21 also tried a different approach

The teacher from Problem 21 also tried a different approach to determining whether changing answers helps or hurts exam grades. In another class, students were told to review their final exams and change any answers they wanted to before turning them in. However, the students had to indicate both the original answer and the changed answer for each question. The teacher graded each exam twice, once using the set of original answers and once with the changes. In the class of n = 22 students, the exam scores improved by an average of MD5 2.5 points with the changed answers. The standard deviation for the difference scores was σ = 3.1. Are the data sufficient to conclude that rethinking and changing answers can significantly improve scores? Use a onetailed test at the .01 level of significance.

**View Solution:**## Answer to relevant Questions

At the Olympic level of competition, even the smallest factors can make the difference between winning and losing. For example, Pelton (1983) has shown that Olympic marksmen shoot much better if they fire between heartbeats, ...a. A repeated-measures study with a sample of n = 16 participants produces a mean difference of MD = 3 with a standard deviation of σ = 4. Use a two-tailed hypothesis test with a = .05 to determine whether this sample ...The following values are from an independent-measures study comparing three treatment conditions. a. Compute the variance for each sample. b. Compute MSwithin, which would be the denominator of the F-ratio for an ANOVA. ...Several factors influence the size of the F-ratio. For each of the following, indicate whether it influences the numerator or the denominator of the F-ratio, and indicate whether the size of the F-ratio would increase or ...The following data summarize the results from an independent-measures study comparing three treatment conditions. a. Use an ANOVA with a = .05 to determine whether there are any significant differences among the three ...Post your question