# Box plot

A box plot shows the five-number summary of the data – the minimum, first quartile, median, third quartile, and maximum. An outlier box plot is a variation of the skeletal box plot that also identifies possible outliers.

## Skeletal box plot

A skeletal box plot shows the median as a line, a box from the 1st to 3rd quartiles, and whiskers with end caps extending to the minimum and maximum. Optional notches in the box represent the confidence interval around the median.

## Outlier box plot

An outlier box plot is a variation of the skeletal box plot, but instead of extending to the minimum and maximum, the whiskers extend to the furthest observation within 1.5 x IQR from the quartiles. Possible near outliers (orange plus symbol) are identified as observations further than 1.5 x IQR from the quartiles, and possible far outliers (red asterisk symbol) as observations further than 3.0 x IQR from the quartiles. You should investigate each possible outlier before deciding whether to exclude it, as even in normally distributed data, an outlier box plot identifies approximately 0.7% of observations as possible outliers.

## Quantile box plot

A quantile box plot is a variation on the skeletal box plot and shows the whiskers extending to specific quantiles rather than the minimum and maximum value.

**Available in Analyse-it Editions**

Standard edition

Method Validation edition

Quality Control & Improvement edition

Ultimate edition

- What is Analyse-it?
- Administrator's Guide
- User's Guide
- Statistical Reference Guide
- Distribution
- Continuous distributions
- Univariate descriptive statistics
- Calculating univariate descriptive statistics
- Univariate plot
- Dot plot
- Box plot
- Mean plot
- Creating a univariate plot
- Frequency distribution
- Normality
- Inferences about distribution parameters
- Discrete distributions
- Study design
- Compare groups
- Compare pairs
- Contingency tables
- Correlation and association
- Principal component analysis (PCA)
- Factor analysis (FA)
- Item reliability
- Fit model
- Method comparison
- Measurement systems analysis (MSA)
- Reference interval
- Diagnostic performance
- Control charts
- Process capability
- Pareto analysis
- Study Designs
- Bibliography

Version 5.30

Published 15-Apr-2019