Let’s look at an example… You have just been hired as a engineer for Apple You are in charge of creating a new and improved battery for the iPhone. Your first task: How does changing the material in the iPhone’s battery affect the life of the battery?

Experiment setup You design a new iPhone battery that has a special chip built inside. You will test to see if this new battery will have a longer life than the normal iPhone battery.

Experiment setup (cont’d) You test 10 brand new iPhones and split them up into two groups of 5: GROUP A (experimental group) 5 new iPhones WITH the special chip inside the battery. GROUP B (control group) 5 new iPhones with the normal battery WITHOUT the special chip. ALL iPhones are brand new, the same model (iphone 5), same size (16 GB), same color (black). Only difference is the special chip inside the batteries in GROUP A. Same wheels, same trucks, same everything So far, what are the CONSTANTS in this experiment?

Setup continued.. Make sure all 10 phones all fully charged. Perform the same activities on each phone: 1-hr long phone call Send 200 text messages Watch 10 youtube videos Listen to 30 songs on itunes. Record the battery life percentage of each phone after all the activities. Calculate the average battery life for GROUP A and for GROUP B

Experimental Setup iPhone battery experiment example: IV: Type of battery (special chip or no special chip) DV: Battery life percentage Constants: All phones brand new Same model (iPhone 5), same size (16 GB), same color (black) All phones had to perform the same activities (1 hr call, 200 texts, youtube, itunes)

Getting accurate and reliable data Experimental vs. Control groups Experimental group: the group where you change the IV Control group: the group where you leave the IV in its natural/normal state Multiple Trials Do the experiment several times