Stats 7 Summer II 2022 Discussion Quiz 1
Full name:_____________________________________
To assess the effectiveness of taking large doses of vitamin C in reducing the duration of the
common cold, researchers recruited 400 healthy volunteers from staff and students at a
university. The patients were randomly assigned to either receive a placebo, 1g Vitamin C, 3g
Vitamin C, or 3g Vitamin C plus additives to be taken at onset of a cold for the following two
days. All tablets had identical appearance and packaging. The duration of cold symptoms was
recorded by rounding up to the nearest day.
(a) What was the goal of this study?
(b) What type of study was this? (Fill in the box to indicate your answer)
Observational
Experimental
(c) Identify the explanatory and response variables and their variable types.
Explanatory variable:
Response variable:
____________________________________
Numerical continuous
Numerical discrete
Categorical regular
Categorical ordinal
____________________________________
Numerical continuous
Numerical discrete
Categorical regular
Categorical ordinal
(d) What type of plot would be appropriate to plot the relationship between these two variables?
Scatterplot
Boxplot for each group
Mosaic plot
Pie chart for each group
(e) Was there random assignment? Yes:
No:
(f) Was there random sampling? Yes:
No:
(g) Is a causal conclusion possible? Yes:
No:
(h) Can the study results be generalized beyond the sample participants? Yes:
No:
(i) Indicate the correct descriptions of the distribution visualized below.
Modality:
Skewness:
Uniform
Symmetric
Unimodal
Left skewed
Multimodal
Right skewed