How to prepare group barplot and error bars with significance using ggplot

In this tutorial, you’ll learn how to create a grouped barplot in R using ggplot2, add error bars (SEM/SD), and overlay statistical significance (p-values / stars) for multiple comparisons. We’ll cover: Reshaping data to long format with pivot_longer() Calculating mean, SD, and SEM for each group Building a grouped (side-by-side) barplot using geom_col() + position_dodge() Adding error bars with geom_errorbar() Running pairwise comparisons (t-test or Wilcoxon) with multiple-testing correction (BH/FDR) Displaying significance brackets and stars using ggpubr / rstatix Polishing the plot: facet labels, theme edits, axis formatting, and legend control By the end, you’ll be able to produce clean, publication-ready plots like the iris example—perfect for presentations, reports, and manuscripts. #RStats #ggplot2 #DataVisualization #Biostatistics #RProgramming #Statistics #ErrorBars#Barplot #GroupBarplot