# Normal Probability Plot in R using ggplot2

A normal probability plot is a graphical representation of the data. A normal probability plot is used to check if the given data set is normally distributed or not. It is used to compare a data set with the normal distribution. If a given data set is normally distributed then it will reside in a shape like a straight line.

In this article, we are going to use ggplot2 with qqplotr to plot and check if the dataset is normally distributed using qqplot only.

### Approach

- Install the following necessary libraries by pasting them in r console

install.packages(“ggplot2”)

install.packages(“qqplotr”)

- Create a random data set with a different mean and standard deviation that you want to plot.
- Plotting data using
**stat_qq_point()**method. - Plotting data points with line using
**stat_qq_line()**function.

Given below is a proper implementation using the above approach

**Example 1:** Plotting data using **stat_qq_point()** method.

## R

`# importing libraries` `library` `(ggplot2)` `library` `(qqplotr)` `# creating random data` `random_values = ` `rnorm` `(500, mean = 90, sd = 50)` `# plotting data without line and labels` `ggplot` `(mapping = ` `aes` `(sample = random_values)) + ` `stat_qq_point` `(size = 2)` |

**Output:**

**Example 2**: Plotting data points with line using **stat_qq_line()** function.

## R

`# importing libraries` `library` `(ggplot2)` `library` `(qqplotr)` `# creating random data` `random_values = ` `rnorm` `(500, mean = 90, sd = 50)` `# plotting data with proper labels` `# And adding line with proper properties` `ggplot` `(mapping = ` `aes` `(sample = random_values))` `+ ` `stat_qq_point` `(size = 2,color = ` `"red"` `)` `+ ` `stat_qq_line` `(color=` `"green"` `)` `+ ` `xlab` `(` `"x-axis"` `) + ` `ylab` `(` `"y-axis"` `)` |

**Output:**