Your TA's name__________________
Your data set number______________
Lab D (Tests Subsequent to ANOVA)
An experimenter was interested in the effects of amphetamine on activity in rats. He randomly assigned 60 rats to five groups. Group 1 received a saline control and groups 2, 3, 4, and 5 received 4, 5, 40, and 50 milligrams of amphetamine, respectively. Activity was measured as the number of times each rat crossed the middle of the testing arena. The experimenter hypothesized that amphetamine would cause significantly greater activity than the saline control, and that the highest dosage of amphetamine would cause significantly greater activity than the lowest dosage. In your response to the questions, use the data set assigned to you by the teaching assistant.
1. Identify the independent and dependent variables.
2. State the null hypothesis in both words and symbols.
3. Perform an ANOVA and present the summary table of your analysis.
4. Present a table of a complete set of orthogonal coefficients that would include tests of the experimenter's hypotheses.
5. Perform the orthogonal comparisons of the experimenter's hypotheses based on the coefficients derived above.
6. Perform Scheffe tests that would test the same hypotheses.
7. Are orthogonal comparisons or Scheffe tests more powerful? Why?
8. Draw the appropriate conclusions concerning the experimenter's hypotheses.