General instructions. This assignment is to be done in your lab session. Submit your assignment from the lab computer during lab time. If the assignment involves SPSS, be sure that when you open SPSS, you set it so that commands are displayed in the output: Edit -> Options, Viewer tab, check box Display commands in the log.

Our goal in this lab exercise is to do some real-world data analysis involving multiple contrasts in oneway ANOVA. Click this link to get the data file from Experiment 1 of Kruschke (1993). The task and design were discussed in class.

* Very briefly explain the planned contrasts you would make, based on the theoretical motivation and design of the experiment. (You might type this into a text document, then copy and paste it into your SPSS output later.)

* Check for outliers within conditions, using a boxplot in SPSS. Should you leave them in or exclude, and why?

* Check for approximate normality, using a boxplot and info from Explore in SPSS. Describe your considerations.

* Check for homogeneity of variance, using the Levene test option in Oneway ANOVA.

* Assuming that the above checks raise questions about the distributions, transform the data appropriately. For example, try arcsin of proportion correct. Re-do the above three checks.

* Do the planned contrasts in Oneway ANOVA in SPSS. Important: What is the significance level for the Bonferroni corrected tests? Which contrasts are significant at that level?

* Suppose you wanted the freedom to do any post-hoc contrast. What would be the critical F value for the contrasts if you used the Scheffe correction?

What to turn in and how to turn it in. Delete everything from your SPSS output file except the tables or graphs you want to submit. Carefully type in brief answers to the above questions so that your answers (and the question you are answering!) are easy to identify. Save a copy of the output file for your own records, and upload a copy to the Assignment 4 link in Oncourse.