Mosaic Plot

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. More people died than survived.

Q2 Describe the largest group that didn’t survive. Discuss by class and gender.

The largest nonsurviving group would be 3rd class male passengers.

Q3 Describe the largest group that did survive. Discuss by class and gender.

The largest surviving group would be 1st class female passengers.

Q4 Describe one group that has more cases than expected given independence (by chance). Discuss by class and gender.

The largest group with more cases than expected would be 3rd class male passengers who did not survive. Likewise, 1st class female passengers, by chance, had more survivors than expected.

Q5 Describe one group that has less cases than expected given independence (by chance). Discuss by class and gender.

3rd class male passengers that did survive had fewer survivors than expected. 1st class female passengers had less cases of survivors 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. More patients did not improve. Q2: The largest group that did not improve would be patients that did not receive treatment. Q3: The largest group that did improve most would be treated patients that showed marked improvement. Q4: Treated patients that showed marked improvement had more cases than expected of improvement. Q5: The pateint group that was not treated and showed marked improvement showed fewer 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.

Q9 Display the title and your name correctly at the top of the webpage.

Q10 Use the correct slug.