A researcher conducts a study on the effects of amount of sleepon creativity. Twenty subjects come to the researcher’s clinic. Theresearcher divides the subjects into four groups, each containingfive subjects. Each group sleeps at the clinic for a differentamount of time (2, 4, 6, or 8 hours). After awakening, each subjecttakes a test of creativity. The following table shows thecreativity scores for the subjects in each group:
Amount of Sleep (in hours) |
2 | 4 | 6 | 8 |
3 | 4 | 10 | 10 |
5 | 7 | 11 | 13 |
6 | 8 | 13 | 10 |
4 | 3 | 9 | 9 |
2 | 2 | 10 | 10 |
- State the appropriate null and alternative hypotheses
- Fill in the blanks in the following summary (source) tabledescribing the results of the ANOVA:
Source | df | SS | MS | F |
Between-groups | | 187.75 | | |
Within-groups | | | | |
Total | | 242.95 | | |
- Find the critical value of F. Assume a level of significance of.05.
- Based on the results of the ANOVA, what is the correctconclusion regarding the null hypothesis?
- What does this result mean in terms of the alternativehypothesis?
- Should you perform a post hoc test in this case? Explain why orwhy not. What information does the post hoc test provide?
- Conduct a Tukey’s HSD test to test the differences between allpossible pairs of sample means at the .05 level of significance andcomplete the following table.
Comparison | X-X | Q |
2hrs – 4hrs | | |
2hrs – 6hrs | | |
2hrs – 8hrs | | |
4hrs – 6hrs | | |
4hrs – 8hrs | | |
6hrs – 8hrs | | |
- What is the value of QCRIT?
- Which pairs of sample means are significantly different?
