The anticoagulant warfarin is often used as a pesticide against house mice, Mus musculus. Some populations of the house mouse have acquired a mutation in the vkorc1 gene from hybridizing with the Algerian mouse, M. spretus (Song et al. 2011). In the Algerian mice, this gene confers resistance to warfarin. In a hypothetical follow-up study, researchers collected a sample of house mice to determine whether presence of the vkorc1 mutation is associated with warfarin resistance in house mice as well. They fed warfarin to all the mice in a sample and compared survival between the individuals possessing the mutation. a. Identifiy the two variables measured in the study and indicate which is the explanatory and which is the response variable.
i. Explanatory:
ii. Response:
b. Identify the scales on which each of the two variables is quantified (nominal, ordinal, inteval, ratio).
c. What do you think was the intended target population for the study? Why?
d. Do you consider the follow up study to be a manipulative experiment or an observational experiment? Explain.
e. Do you think the researchers used a random sample? Explain.

Solution :

Response variable is the variable whose value is to be predicted or the value  is influenced. It is also known as the dependent variable. While the variable which affects the values and is used for the prediction is known as the explanatory variable or the independent variable.

i. The explanatory variable in the study is the Vkorc I mutation.

ii. The response variable in the study is the Warfarin resistance.

b). The explanatory variable which comes under the nominal scale in this study is the Vkorc I mutation.

While the response variable or the independent variable that comes under the interval scale in the study is the Warfarin resistance.

c). The group of the individuals in this study is called as  population. The target population in the study is the house mouse which is required as the mutation in Vkorc 1 gene from the hybridizing with Algerian mouse.

d). The study is a manipulative experiment as the changes that have already introduced in house mice and the treatments are under control.

e). No in this study the researcher did not use any random sample.

i leave the calculator work to you.

7. diameter 4 miles, circumference 4π miles

8. radius 0.2 miles, circumference 0.4π miles

[this is a bad problem because the actual radius of a car on the track is less than 0.2 miles so the answer is less than 0.4π miles]

9. radius 6 feet, circumference 12π feet

10. diameter 14 cm, circumference 14π cm

11. diameter 4.8 feet, circumference 4.8π feet