# Plot Group Means and Confidence Intervals - R Base Graphs

Previously, we described the essentials of R programming and provided quick start guides for importing data into R.

Here, we’ll describe how to create mean plots with confidence intervals in R.

1. Launch RStudio as described here: Running RStudio and setting up your working directory

2. Prepare your data as described here: Best practices for preparing your data and save it in an external .txt tab or .csv files

3. Import your data into R as described here: Fast reading of data from txt|csv files into R: readr package.

Here, we’ll use the R built-in ToothGrowth data set.

# Data

``head(ToothGrowth)``
``````##    len supp dose
## 1  4.2   VC  0.5
## 2 11.5   VC  0.5
## 3  7.3   VC  0.5
## 4  5.8   VC  0.5
## 5  6.4   VC  0.5
## 6 10.0   VC  0.5``````

# Plot group means

The function plotmeans() [in gplots package] can be used.

``````library(gplots)
# Plot the mean of teeth length by dose groups
plotmeans(len ~ dose, data = ToothGrowth, frame = FALSE)``````

``````# Add mean labels (mean.labels = TRUE)
# Remove line connection (connect = FALSE)
plotmeans(len ~ dose, data = ToothGrowth, frame = FALSE,
mean.labels = TRUE, connect = FALSE)``````

# Infos

This analysis has been performed using R statistical software (ver. 3.2.4).

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