1. Principles of Data visualization

Data visualization plays at least two critical roles in medical and health research. The first, more prominent role is the visualization of research results to support their interpretation. The second, less glamorous role is in the exploration of research data in order to confirm its contents, completeness and quality. In my own work as a statistician, I spend a lot more time making plots, the vast majority of which are never seen by another human, than I do analyzing data with statistical models. This contrasts with what I believe is a common perception that visualizing data is some how tangential or secondary to data analysis. Nothing could be further from the truth and so we will spend a good bit of time on our data visualization skills.

The specific tool we will use for data visualization is the R package ggplot2. However, before we dive into the specifics of code, I was to introduce what I think are the key principles of data visualization that you might think about before actually sitting down to create a particular figure or other visualization.