Question

Consider a study in which neurologists want to determine if taking an intravenous dose of vitamin C will reduce the amount of nerve pain reported by patients. Suppose that the study was narrowed to focus only on patients with the nerve disorder multiple sclerosis (MS). After study approval, the neurologists solicit volunteers who are patients with MS who are reporting pain. The participants are then randomly assigned to two groups, each having 20 participants.

Participants in Group A are administered intravenous doses of vitamin C, and their nerve pain is tracked. Participants in Group B are administered intravenous doses of saline (which has no active ingredients) and their pain levels also tracked. The patients are not told which of the two groups they are in; however, the nurses administering the IVs are aware of the group assignments. After a predetermined length of time, the amounts of pain reported by the separate groups are compared to determine if an intravenous dose of vitamin C will reduce the amount of nerve pain.

a. Identify the explanatory and response variables.

b. What is the treatment?

c. Which group is the treatment group and which group is the control group?

d. What is the purpose of administering saline to Group B?

e. Is this a single-blind or double-blind study? Do you think this is the best choice for this study?

Answer 1

(a)

Explanatory Variable: Intraveneous dose of vitamin C

Response Variable: the amount of nerve pain reported by patients

(b)

The treatment: (i) administering Intraveneous dose of vitamin C and (ii) administering Intraveneous dose of saline

(c)

Treatment group: Group A who are administered Intraveneous dose of vitamin C

Control Group: Group B who are administered Intraveneous dose of saline

(d)

The purpose of administering saline to Group B is to allow the researcher to minimize the effect of all variables except the independent variable. The control group receiving no intervention is used as a baseline to compare groups and assess the effect of that intervention.

9e)

This is a single blind study.We do not think this is the best choice for this study because in this study each participant is aware to which group he belongs and this knowledge will indirectly affect his response to the treatment, thus making the result unreliable.