Design, carry out, and analyze your own multifactor experiment. The experiment doesn’t have to involve human subjects. In fact, an experiment designed to find the best settings for microwave popcorn, the best paper airplane design, or the optimal weight and placement of coins on a toy car to make it travel farthest and fastest down an incline are all fine ideas. Be sure to define your response variable of interest before you start the experiment and detail how you’ll perform the experiment, specifically including the elements you control, how you use randomization, and how many times you replicate the experiment.
Analyze the results of your experiment and write up your analysis and conclusions including any recommendations for further testing.