Creating Understandable Data Visualizations in R

Data visualization is central to scientific communication, yet many clinicians and early-career researchers struggle to create clear and interpretable figures.This article presents a beginner-friendly approach to building charts in R using the grammar of graphics framework.Every element of a chart is a choice, and the default is rarely the best one.Using a simulated clinical dataset of systolic blood pressure across treatment groups, we demonstrate how plots are constructed explicitly by combining data, aesthetic mappings, and geometric representations.Through stepby-step examples, we show how deliberate layering of axis labels, titles, color palettes, and themes transforms a bare-minimum plot into a publication-ready figure.By emphasizing deliberate decision-making over reliance on software defaults, this work aims to lower barriers to effective data visualization and support transparent scientific reporting.