Question

In a study to investigate whether vitamin C is an effective treatment for colds, volunteers who caught a cold after having been exposed to various cold viruses are assigned at random to one of two groups. The 10 volunteers in the experimental group were given tablets containing 1 gram of vitamin C to be taken four times a day. The 12 volunteers in the control group were given placebo tablets. The length of time (in days) the cold lasted for each volunteer was then recorded. The mean length of time the cold lasted for volunteers in the experimental group was found to be 6.45 with a standard deviation of 0.76, while the mean length of time the cold lasted for volunteers in the control group was found to be 7.13 with a standard deviation of 0.88.

(a) Is there evidence to indicate that taking 4 grams daily of vitamin C reduces the mean length of time a cold lasts? Conduct the appropriate test of hypothesis at the 5% level of significance.

(b) What assumptions are necessary for your test to be statistically valid?

Answer 1

(a)

Let group 1 is the group taking 4 grams daily of vitamin C and group 2 is the control group.

Cpnclusion: There is evidence to conclde that taking 4 grams daily of vitamin C reduces the mean length of time a cold lasts.

(b)

Since sample sizes are small so we need to assume that populations under study are normally distributed. That is data of both groups are normally distributed