Dr. James isolated Staphylococcus aureus, a type of bacteria, from the leg wound of a ten year old boy. He suspected these bacteria would grow better at body temperature than room temperature (72oF), but thought that he should collect data to support his thinking. Dr. James introduced the same number of Staphylococcus bacteria into each of six test tubes containing the same type and amount of nutrient broth. Three test tubes were incubated at 98.6oF (Group 1), while three test tubes (Group 2) sat at 72oF. After 24 hours, Dr. James compared the turbidity (indicative of growth) of all six tubes and rated each on a scale of 0 - 4. 0 indicates no turbidity (no growth), while 4 indicates high turbidity (high growth). The data below was collected. The dependent variable in this experiment is:.