Hot Chocolate Experiment Have you ever stirred your hot chocolate and noticed that the pitch increases as you continue to tap?  Here are recordings of the tapping sound under different conditions. Condition #2: Does the cup's contents impact the change in pitch? Here we tested 3 different kinds of liquids: hot water, water with cocoa, and water with cocoa after it's sat for a while. Null Hypothesis:  There is no difference in the tapping pitch characteristics among different kinds of liquids. Here are recordings of what the tapping sounded  like for each cup filled with different liquids: Regular mug with hot water Regular mug with fresh cocoa  Regular mug with cocoa after it's sat for a while  Here is the wide mug with different liquids: Wide mug with hot water Wide mug with fresh cocoa Wide mug with cocoa after it's sat for a while Here is the plastic mug with different liquids: Plastic cup with hot water Plastic cup with fresh cocoa Plastic cup with cocoa after it's sat for a while   Questions: Do you think the data proves that the null hypothesis true or false?  Why or why not? It is possible to rearrange this data to test at least one other condition.  How could you rearrange the data, and what might you test?  Let's say that we test hot water with three different mugs (normal, wide and plastic).  What would be the null hypothesis?  Would this null hypothesis be true or false? Back to the main page.