Question

Dr. Trudeau’s little experiment had a big impact on medical thinking at the time. His experiment offered a rationale for opening his Adirondack Cottage Sanitarium, which offered rich and poor alike a regimen of abundant nourishing food, lots of sunlight, plenty of rest, and as much fresh air as a person could tolerate. Hundreds were helped, and many similar establishments were opened. Perhaps the experiment was so successful because of the care with which Trudeau had designed its components. It is important to identify an interesting and potentially approachable question or set of questions before undertaking an experiment. But it is just as important to devise a clever experimental design. When we design an experiment, we choose the treatments that will be received and we control or manipulate them in appropriate ways. These treatments or manipulations are the independent variable(s). The observed or measurable differences in outcome for the treatment groups are the dependent variable(s). Suppose I want to know how much sunlight is needed to produce the sweetest oranges? Based on what I know about sunlight and photosynthesis, I hypothesize that the greater amount of sunlight an orange plant gets, the sweeter the juice of the orange. To investigate whether this is true, I might place one group of plants in the sun for 2 hours per day, another group for 4 hours per day, and nother group for 8 hours per day. At the end of the experiment, I could test for the amount of sugar in the juice of the oranges. The amount of time in the sun is the independent variable. The sugar in the juice is the dependent variable.

7. What is the dependent variable in the Rabbit Island Experiment? Also, list all of the independent variables you can think of in the experiment. (Hmm, maybe Dr. Trudeau’s experiment was not so simple after all!)

8. Often, scientists like to hold all conditions constant except one. Just varying one thing at a time makes it easier to analyze the results. Select any one of the independent variables you have listed above and design an experiment similar to Dr. Trudeau’s. State your experimental question, i.e., what are you trying to find out. Formulate a hypothesis. Then decide upon and write out a description of how you will manipulate your treatment groups (there needn’t be three; you could have two, or four—just design a good experiment!), and then imagine the possible outcomes, assuming survival is the dependent variable. Now generate two survival curves based on those imagined outcomes—one that supports your hypothesis and one that does not. Give possible percent survival rates for each experimental group under both outcomes.

Answer 1

In the case of the rabit island experiment it has been seen that the tiberculosis is caused by the bad air and the contaminated environment which is present around the rabits unless neglecting the fact of the presence of pathogens. Dr. trudeau has got TB while taking care of his brother and he has observed that the TB can cause high when the patient is around the healthy person and there is lack of ventilation, fresh air etc. Hence in the case of the rabbit experiments the following facts must have been taken into the consideration.

• The infected rabbit with the cramped conditions
• The healthy rabbit with cramped condition
• The infected rabbit with the healthy conditions

Thus here the incubation of the rabbit for the particular month number will be the independent variable while that of the survive rate is the dependent condition to understand which is the factor that plays a critical role for overtaking the fact of the reason behind TB.