Question

Satisfied with the great investigative work that you did in the town of Idyllic, you head for home. On your way, you stop for a rest in a nearby town, LessThanIdyllic. It is very similar to its sister town, with a population of Simploids that make the town population nearly as happy as in Idyllic. The biggest difference is that the parasitic Shamworms are endemic to LessThanIdyllic. Like Idyllic, the Simploids in LessThanIdyllic have been getting sick and the citizens are getting worried. Word of your investigation has reached the town and so you are approached by the mayor to see if you can determine if it is the town’s use of ZapWeedz in their public parks that is the reason that their Simploids are getting sick.

1. What is an appropriate null hypothesis for the experiment you will run in LessThanIdyllic? (1)

2. What is the independent variable? (1)

3. What is the dependent variable? (1)

4. What is the experimental treatment? (1)

5. What is the control treatment? (1)

6. What are two (2) other potentially confounding variables you will need to keep constant? (1)

Answer 1

- Null hypothesis

Remember the null hypothesis will always unrelate your suspected factor/treatment to the difference/result, so in this case it is: Zapweedz are not related to the disease incidence.

- Independent variable

From this point we have to start to figure an actual experiment to address the issue. In this case we could make different treatments, where we are going to expose different individual groups to the Zapweedz, and we are going to register the disease occurance in such groups. Remember that the independent variable is the one that we are controling, in this case it is the level of exposure to Zapweedz

- Dependent variable

Using the same idea as the previous question, remember the dependent variable is the one that will vary according to the independent variable, so in this case it is the proportion of sick people in the groups.

- Experimental treatment

The experimental treatment will be the different levels of exposure to the Zapweed

- Control treatment

We need a control, clearly, so the control will be a treatment in a group of individuals where the exposure to Zapweedz will be 0, no exposure at all.

- Confounding variables

A confounding variable is such that may produce variability in the dependent variable, without having nothing to do with our independent variable of interest, so the effecy of such confounding variable would mess up our results and we might end up concluding something wrong. When we are tlaking about health a very common confounding variable is the age of the individuals (as it is a major factor for disease vulnerability), along with it we may take another factor related to vulnerability levels, such as medical treatment use, so we have to make sure that none of our individuals is under medication and around the same age.