Montarello and Martens (2005) found that 5th grade students completed more mathe
ID: 3059724 • Letter: M
Question
Montarello and Martens (2005) found that 5th grade students completed more mathematics problems correctly when simple problems were mixed in with their regular math assignments. To further explore this phenomenon, suppose that a researcher selects a standardized mathematics achievement test that produces a normal distribution of scores with a mean of µ = 100 and a standard deviation of = 18. The researcher modifies the test by inserting a set of very easy problems along with the standardized questions and gives the new modified test to n = 36 students. The average test score for the sample is M = 104. The researcher is interested in whether or not the modified test results in improved performance.
20. State the null hypothesis:
21. For a one-tailed test, = 0.01, the critical region consists of z-scores beyond:
22. Calculate standard error (M) for this sample.
23. Calculate z for this sample:
24. What is your conclusion (reject or fail to reject H0)?
25. What does your conclusion mean?
26. When should you use a t-test instead of a z-test?
Explanation / Answer
20)
21)
22)
23)
24) as test statistic is not higher than critical value fail to reject H0
25)
we do not have evidence to conclude that modified test results in improved performance
26)
we use t test when population std deviation is not known,.
null hypothesis: = 100 Alternate Hypothesis: > 100