Mosaic Plot
Raven Silver
10/8/2019
In this exercise you will learn to visualize the pairwise relationships between a set of quantitative variables. To this end, you will make your own note of 8.5 Mosaic plots from Data Visualization with R.
Mosaic charts can display the relationship between categorical variables using:
- rectangles whose areas represent the proportion of cases for any given combination of levels, and
- the color of the tiles to indicate the degree relationship among the variables.
The Titanic data set came from https://osf.io/aupb4/.
In the graph below,
- dark blue represents more cases than expected given independence (by chance); and
- dark red represents less cases than expected if independence holds (by chance).
Q1 Did more passengers survive?
No, because there is a much larger death rate.
Q2 Describe the largest group that didn’t survive. Discuss by class and gender.
The largest group that didn’t survive were 3rd class males.
Q3 Describe the largest group that did survive. Discuss by class and gender.
The largest group that did survive were 1st class females.
Q4 Describe one group that has more cases than expected given independence (by chance). Discuss by class and gender.
3rd class males that didn’t survive have more cases than expected.
Q5 Describe one group that has less cases than expected given independence (by chance). Discuss by class and gender.
3rd class males that did survive have less cases than expected.
Q6 Create a mosaic plot for Arthritis in the same way as above.
Hint: The Arthritis data set is from the vcd package. Add an additional argument gp = shading_max in the mosaic function. This is because the residuals are too small to have color.
Q7 Repeat Q1-Q5.
Q1. No, because there is a much larger group of people who haven’t improved.
Q2. The largest group that didn’t improve were people who used the placebo.
Q3. The largest group that did improve were people who were treated.
Q4. People who were treated and marked have more cases than expected.
Q5. People who used the placebo and marked have less cases than expected.
Q8 Hide the messages, the code and its results on the webpage.
Hint: Use message, echo and results in the chunk options. Refer to the RMarkdown Reference Guide.