one tailed tests

Question

A teacher wants to improve test scores in her class so she decides to see if group exams work. The average in her past classes was 70 with a standard deviation of 7. After testing her class of 36, their average was 75. Was there an increase?

a. What are the groups?

What is the dependent variable?

b. What are the null and research hypotheses?

c. What are the numbers needed to compute the formula?

d. What is the z statistic?

e. For a one tailed test at .05 significance, the critical value is 1.65. What decision do we make?

f. What is the effect size? (M-μ/σ)

Answer 1

a. past classes and sample class

dependent variable is test score

b. Ho: mean score = 70

Ha: mean score > 70

c. past class score and standard deviation, sample mean score and sample size

d. z = (sample mean - past mean)/(past SD/sqrt(sample size)) = (75-70)/(7/sqrt(36)) = 4.28

e. reject Ho

f. (75 - 70)/7 = 0.714