As an admissions counselor, I am interested in understanding whether or not there is a difference in stress levels not only between different majors but also between different classes (Freshman v. Seniors). I gather the following data from students from three majors (Psychology, Chemistry, and Engineering), that are in their freshmen or senior years and ask them about their stress levels (scale of 1-10, with lower numbers meaning less stress). Using the data below, test whether there are effects of class, major, or an interaction between them at an alpha of 0.05.    Psychology Chemistry Engineering Freshmen 3, 4, 4, 2, 4 4, 5, 7, 8, 4 5, 7, 7, 8, 5 Senior 4, 5, 5, 3, 5 8, 5, 6, 7, 7 9, 9, 8, 7, 9 Complete the ANOVA summary table below:

What are the requirements for an experiment to be able to show that changes in one variable cause changes in another?

Read through this scenario and look at the data that was collected.  State the null and all possible research hypotheses.  Review the results below (I used SPSS) and answer the questions that follow. Scenario:  A researcher wants to see if gender and / or income affects the total amount of help given to a stranger who is sitting on the side of a busy road with a sign asking for help.  The independent variables are gender, income, and the interaction of gender and income.  The dependent variable is total help. He wants to know if one or both factors – or the interaction of the two - affects the total amount of help offered.  Because he is analyzing two independent variables (gender and income), he used a factorial ANOVA.  His results show the main effect of each of the independent variables on the dependent variable (total help) and the interaction effect.  The researcher is using a 95% confidence interval which means that he wants to be at least 95% sure that his independent variables…

A researcher conducts an independent-measures study to examine how the brain chemical serotonin is related to aggression.  One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin.  A second sample of rats, low serotonin group, receives a drug that lowers brain levels of serotonin.  Then, the researcher tests the animals by recording the number of aggressive responses each of the rats display.  See the data below. Is there a significant difference between the control group and the low serotonin group regarding the number of aggressive responses?                                                Control         Low Serotonin                                                    n = 10                 n = 15                                                M = 14               M = 19                                                SS = 180.5         SS = 130 Perform a hypothesis test using independent-measures t-test. Use a two-tailed…